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Universität Stuttgart Institut für Physikalische Chemie

Stuttgart, 23-25 September 2019

Colloid-Conference ,,Complex Fluids"

49th General Meeting of the German Colloid Society

Book of Abstracts and Program

Conference chairs:

Cosima Stubenrauch Peer Fischer Frank Gießelmann Thomas Sottmann

Program committee:

Siegfried Dietrich Hans-Jürgen Butt André Laschewsky

Address: Universität Stuttgart Institut für Physikalische Chemie Pfaffenwaldring 55 70569 Stuttgart Germany

www.ipc.uni-stuttgart.de

e-mail: colloid19@ipc.uni-stuttgart.deWebsite: http://colloid19.ipc.uni-stuttgart.de

List of Sponsors

Anton Paar Graz, Österreich

Bruker Karlsruhe, Germany

DataPhysics Instruments GmbH Filderstadt, Germany

Springer Heidelberg, Germany

Fritz Henkel StiftungDüsseldorf, Germany

Table of Contents

General Information ............................................................................ 7

Schedule ........................................................................................... 10

Scientific Program ............................................................................. 11

List of Posters ................................................................................... 15

Abstracts of Plenary and Award Lectures .......................................... 19

Abstracts of Special Lectures ............................................................ 33

Abstracts of Posters .......................................................................... 71

List of Contributors .......................................................................... 104

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6

General Information

Venue

All sessions are performed at the ETI (Informatik, Elektrotechnik und Informationstechnik), Campus of the University of Stuttgart in Stuttgart-Vaihingen, Pfaffenwaldring 47

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Language

The official language of the conference is English

Registration

The registration will take place in the Foyer of Pfaffenwaldring 47

Monday, September 23, 11:00 – 19:00Tuesday, September 24, 8:30 – 18:00

Please be aware that only persons wearing badges of the conference can enter the lecture halls and can attend the conference dinner.

Internet

To connect to the internet:

Eduroam: Please verify at your home institution how to get access Guest network: User name: konferenz

The password is available at the conference office

Presentations

The conference presentations consist of plenary/award lectures and of special lectures. Poster sessions: Monday, September 23, 14:35 – 16:00

Tuesday, September 24, 14:15 – 16:00. Plenary lectures are 40 min long, including questions and discussions. Special lectures are 20 min long, including questions and discussions.

Presentations should be uploaded on the presentations laptops. Please do so latest in the break before your session.

Recording of the lectures is not allowed. The organizers reserve the right to take photographs for documentation during the meeting.

Poster size should be A0 portrait or smaller. Materials for fixing posters will be provided on site. Posters can be mounted at the beginning of the conference and should be removed on Wednesday.

Five poster prices are kindly donated by Springer and the Kolloid-Gesellschaft. A scientific committee will evaluate them during the poster sessions. The prices will be awarded at the conference dinner.

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Refreshments (included in the conference fee)

Refreshments will be served during the coffee breaks

Lunch (not included in the conference fee) A small (and by no means complete) selection of places which are easily accessed during lunch breaks and for dinner.

... on campus: Mensa Vaihingen Pfaffenwaldring 45 70569 Stuttgart

Campus.guest Universitätsstraße 34 70569 Stuttgart

Ristorante La Bruschetta Pfaffenwaldring 62 70569 Stuttgart

Tavena Elia & Restaurant Pfaffenwaldring 62 70569 Stuttgart

... close to „S-Bahn Feuersee“:Two stops (7 minutes) from

„Universität“ by S-Bahn

Trollinger Steak & Brauhaus Rotebühlstraße 50 70178 Stuttgart

Brauereigasthaus Sanwald Silberburgstr. 157 70178 Stuttgart

... close to „S-Bahn Stadtmitte“ Three stops (9 minutes) from „Universität“ by S-Bahn

From the S-Bahn station “Stadtmitte” you easily access the “Calwer Straße” with a lot of restaurants, snack bars and pubs. Here is just one example:

Paulaner am alten Postplatz Calwerstraße 45 70173 Stuttgart

Conference dinner (included in the conference fee)

On Tuesday, September 24, 19:30, the conference dinner is going to take place at the Campus.guest, Universitätsstraße 34. Please remember to wear your badge. Enjoy Italian starters, Swabian and other main courses, different desserts, white, rose and red wine, beer and softdrinks.

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Schedule

Tuesday, September 24, 2019 Plenary Session (47.03)

09:00-09:40 PL5: O. Velev 09:40-10:20 PL6: V. Schmitt (Springer Lecture) 10:20-10:50 Coffee Break

Self-Assembly (47.03) Microgels (47.05) Methods (47.06)

10:50-11.10 SL10: T. Hellweg SL13: M. Kühnhammer SL16: D. Vasquez 11:10-11.30 SL11: T. Kottke SL14: S. Schneider SL17: A. J. Schmid 11:30-11:50 SL12: M. Gradzielski SL15: A. Scotti SL18: A. Wittemann 11:50-13:15 Lunch Break

Microgels (47.03) Colloid Dynamics (47.05) Materials (47.06)

13:15-13:35 SL19: A. Scotti SL22: P. Lettinga SL25: J. Koetz 13:35-13:55 SL20: L. Zeininger SL23: D. Botin SL26: T. Quan 13:55-14:15 SL21: F. Jung SL24: E. Bartsch SL27: S. Schlappa 14:15-16:00 Poster Session / Coffee Break

Plenary Session (47.03)

16:00-16:40 PL7: D. Kraft 16:40-17:20 PL8: T. Kraus (Liesegang Award Lecture) 17:30-18:30 General Assembly of the Members of the Kolloid-Gesellschaft

19:30- Conference Dinner

Wednesday, September 25, 2019 Plenary Session (47.03)

09:00-09:40 PL9: M. Borkovec (Graham Award Lecture) 09:40-10:20 PL10: J. Lagerwall 10:20-10:50 Coffee Break

Self-Assembly (47.03) Liquid Crystals (57.05) Colloid Manipulation (47.06)

10:50-11.10 SL28: C. Papadakis SL31: C. Schmidt SL34: S. Disch 11:10-11.30 SL29: F. Gröhn SL32: K. Koch SL35: M. Retsch 11:30-11:50 SL30: J. Crassous SL33: J. Bruckner SL36: Y. Alapan 11:50-12:00 Break

Plenary Session (47.03) 12:00-12:20 PL11: A. Gröschel (Zsigmondy Award Lecture) 12:20-13:00 PL12: B.P. Binks 13:00-13:15 Closing Remarks

Monday, September 23, 2019 Plenary Session (47.03)

13:00-13:15 Welcome Address 13:15-13:55 PL1: D. Langevin (Ostwald Award Lecture) 13:55-14:35 PL2: C. Bechinger 14:35-16:00 Poster Session/Coffee Break

Active Colloids (47.03) Surfactant Self-Assembly (47.05)

Applications (47.06)

16:00-16.20 SL1: A. Eremin SL4: I. Hoffmann SL7: J. Gutmann 16:20-16.40 SL2: M. Heidari SL5: H. Frielinghaus SL8: J. Venzmer 17:00-17:20 SL3: M. Popescu SL6: V. J. Spiering SL9: S. Andrieux 17:20-17:30 Break

Plenary Session (47.03) 17:30-18:10 PL3: A. Salonen 18:10-18:50 PL4: W. Kunz (Steinkopff Award Lecture)

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Scientific Program PL: plenary lecture; SL: special lecture

Monday, September 23, 2019

Plenary Session (47.03) Chair: M. Gradzielski 13:00-13:15 Welcome Address: C. Stubenrauch 13:15-13:55 PL1: D. Langevin (Ostwald Award Lecture) “Emulsion stability in systems with ultralow oil-water interfacial tension” 13:55-14:35 PL2: C. Bechinger “Group formation and cohesion of active particles with visual perception-dependent mobility” 14:35-16:00 Poster Session / Coffee Break

Active Colloids (47.03) Chair: T. Hellweg

Surfactant Self-Assembly (47.05) Chair: W. Kunz

Applications (47.06) Chair:A. Wittemann

16:00-16:20 SL1: A. Eremin Institute of Physics, University Magdeburg “Entrainment dynamic of anisometric particles in an active bath”

SL4: I. Hoffmann Institute Laue-Langevin, Grenoble “Influence of Surfactant Chain Length on the Viscosity in Polyelectrolyte / Surfactant Complexes”

SL7: J. Gutmann Deutsches Textilforschungszentrum NordWest “Carbon Nanofibers (CNFs) from Electrospun Polyacrylonitrile (PAN) Nanoparticle Composites”

16:20-16:40 SL2: M. Heidari Department of Physics, TU Darmstadt “The Impact of Brush/Water Interface on the self-propulsion of Janus Particles”

SL5: H. Frielinghaus Forschungszentrum Jülich, MLZ “Microemulsions at planar surfaces with and without flow”

SL8: J. Venzmer Evonik Nutrition & Care GmbH, Essen “Superspreading - Has the mystery been unraveled?”

16:40-17:00 SL3: M. Popescu MPI for Intelligent Systems, Stuttgart “Rotation of a thermo-chemically active colloid with random surface activity around the center of an optical trap”

SL6: V. J. Spiering Institut für Chemie, TU Berlin “Structure and Phase Behaviour of a New Type of CO2-Containing Dodecylethoxylate Surfactants”

SL9: S. Andrieux Institut Charles Sadron, Strasbourg “Monodisperse Highly Ordered Chitosan/Cellulose Nanocomposite Foams”

17:00-17:10 Break Plenary Session (47.03) Chair: M. Gradzielski

17:10-17:50 PL3: A. Salonen “Interplay of bubbles and drops in foamed emulsions” 17:50-18:30 PL4: W. Kunz (Steinkopff Award) “From colloidal solution chemistry to greener product formulations”

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Tuesday, September 24, 2019

Plenary Session: (47.03) Chair: W. Richtering 9:00- 9:40 PL5: O. Velev “Classical phenomena to new use: Magnetism and capillarity in the making of responsive and active colloidal

structures” 9:40-10:20 PL6: V. Schmitt (Springer Lecture) „Elaboration of double emulsion-based polymeric capsules for fragrance retention”

10:20-10:50 Coffee Break Self-Assembly (47.03) Chair: F. Gießelmann

Microgels (47.05) Chair: C. Papadakis

Methods (47.06) Chair: J. Bruckner

10:50-11.10 SL10: T. Hellweg Department of Chemistry, University Bielefeld “Interaction of the Bio-Surfactant Aescin with biological model membranes”

SL13: M. Kühnhammer Department of Solid State Physics, TU Darmstadt “PNIPAM microgel-stabilized foams studied with neutron scattering”

SL16: D. Vasquez Institute of Chemistry, University of Potsdam “Particle size analysis of highly concentrated phase change dispersions by Photon Density Wave spectroscopy”

11:10-11:30 SL11: T. Kottke Physical and Biophysical Chemistry, Bielefeld University “Formation of 2D Nanomembranes by Photopolymerization of Diacetylene Lipids”

SL14: S. Schneider Institute of Physical Chemistry, RWTH Aachen “Model-based Synthesis of Ferrocene Containing Microgels”

SL17: A. J. Schmid Physical and Biophysical Chemistry, Bielefeld University “Development of a Sample Environment for in-situ Dynamic Light Scattering in Combination with Small Angle Neutron Scattering for the Investigation of Soft Matter at the European Spallation Source”

11:30-11:50 SL12: M. Gradzielski Institut für Chemie, TU Berlin “Directed Assembly of Multi-Walled Nanoribbons and Nanotubes of Amino Acid Amphiphilies using a Layer-by-Layer Approach”

SL15: A. Scotti Institute of Physical Chemistry, RWTH Aachen “Deswelling of microgels in crowded suspensions depends on crosslink density and architecture”

SL18: A. Wittemann Colloid Chemistry, University of Konstanz “Separation of multimodal colloidal mixtures using zonal rotor centrifugation”

11:50-13:15 Lunch Break

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Tuesday, September 24, 2019

Microgels (47.03) Chair: T. Sottmann

Colloid Dynamics (47.05) Chair: P. Fischer

Materials (47.06) Chair: H. Frielinghaus

13:15-13.35 SL19: A. Scotti Institute of Physical Chemistry, RWTH Aachen “Exploring the colloid-to-polymer transition for ultra-low crosslinked microgels from three to two dimensions”

SL22: P. Lettinga Forschungszentrum Jülich “Morphological Influences on the Shear Flow Behavoir of Colloidal Rods”

SL25: J. Koetz Institut für Chemie, Universität Potsdam “Formation of anisotropic gold nanoparticles in AOT-based template phases”

13:35-13:55 SL20: L. Zeininger Max-Planck Institute of Colloids and Interfaces, Potsdam “Stimuli-Responsive Complex Emulsions as Novel Transducers in Chemical and Biological Sensing Application”

SL23: D. BotinInstitut für Physik, JGU Mainz “Measuring Colloidal Dynamics in Turbid Suspensions”

SL26: T. Quan Helmholtz Zentrum Berlin “Highly Dispersible Hexagonal Carbon-MoS2-Carbon Nanoplates with Hollow Sandwich Structures for Supercapacitors”

13:55-14:15 SL21: F. Jung Physics Department, Technical University of Munich “Structural properties of a pH and temperature responsive telechelic pentablock terpolymer in dilute solution”

SL24: E. Bartsch Institute of Physical Chemistry, University Freiburg “Formation of Laves Phases in Repulsive and Attractive Binary Mixtures of Buoyancy Matched Hard Spheres”

SL27: S. Schlappa Institute of Chemistry/Physical Chemistry University of Potsdam “Inline Characterization of highly turbid disperions during emulsion polymerization using Photon Density Wave spectroscopy”

14:15-16:00 Poster Session / Coffee Break Plenary Session (47.03) Chair: C. Schmidt

16:00-16:40 PL7: D. Kraft “Self-assembly of flexible colloidal structures” 16:40-17:20 PL8: T. Kraus (Liesegang Award Lecture) “Hybrid colloids as printable materials” 17:30-18:30 General Assembly of the Members of the Kolloid-Gesellschaft

19:30 Conference Dinner

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Wednesday, September 25, 2019

Plenary Seesion (47.03) Chair: W. Richtering 9:00- 9:40 PL9: M. Borkovec (Graham Award) “Particle Aggregation” 9:40-10:20 PL10: J. Lagerwall “Out of the gel and into the equilibrium liquid crystal: how fractionation of cellulose nanocrystals transforms phase

diagram, cholesteric helix formation and tactoid behavior” 10:20-10:50 Coffee Break

Self-Assembly (47.03) Chair: E. Bartsch

Liquid Crystals (47.05) Chair: A. Gröschel

Colloid Manipulation (47.06) Chair: J. Koetz

10:50-11.10 SL28: C. Papadakis Physik-Department, TU München “All-in-One "schizophrenic" self-assembly of orthogonally tuned thermoresponsive diblock copolymers”

SL31: C. Schmidt Department of Chemistry, Paderborn University “Formation of silver nanoparticles in monoolein-based lyotropic liquid crystals in the absence and presence of DNA”

SL34: S. Disch Department für Chemie, Universität zu Köln “Directing the Orientational Allignment of Anisometric Magnetic Nanoparticles using Dynamic Magnetic Fields”

11:10-11:30 SL29: F. Gröhn Department of Chemistry and Pharmacy, University Erlangen “Supramolecular Colloids with Function-ality and Switchability through Light”

SL32: K. Koch Institut für Physikalische Chemie, Universität zu Köln “Strong ferronematic coupling with anisotropic LC polymer brush particles”

SL35: M. Retsch Physikalische Chemie, Universität Bayreuth “Ordered Particle Arrays via a Langmuir Transfer Process: Large Area Access to Any Two-Dimensional Bravais Lattice”

11:30-11:50 SL30: J. Crassous Institute of Physical Chemistry, RWTH Aachen “Supracolloidal Atomium”

SL33: J. Bruckner Institut für Physikalische Chemie, Universität Stuttgart “Lyotropic liquid crystals as templates for mesoporous silica materials”

SL36: Y. Alapan Physical Intelligence Department, Max Plack Institute, Stuttgart “Shape-directed programmable assembly of colloidal machines”

11:50-12:00 Break Plenary Session (47.03) Chair: C. Stubenrauch

12:00-12:20 PL11: A. Gröschel (Zsigmondy Award Lecture) “Compartmentalized Colloidal Particles” 12:20-13:00 PL12: B. P. Binks “Oil Foams Stabilised by Surfactant or Fat Crystals” 13:00-13:15 Closing Remarks: C. Stubenrauch

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List of Posters Applications & Materials AM1 - Study of Sedimentation Behavior of Mono- and Oligo-Disperse Suspensions with the MultiScan Setup® Hanih Paydar Martin Grüßer, Michaela Laupheimer, Christian Schöttle, Thomas Sottmann

AM2 - Synthesis and characterization of nanoporous polymers and hybrid materials for heterogeneous catalytic applications Karina Abitaev, Yaseen Qawasmi, Petia Atanasova, Joachim Bill and Thomas Sottmann

AM3 - Magnetic Nanoparticle/Polymer Brush Composite Materials: Adsorption Behaviour and Structure Philipp Ritzert, Dikran Boyaciyan, Larissa Braun, Olaf Soltwedel, Luca Silvi, Regine v. Klitzing

AM4 - Iron Oxide Nanoparticles Encapsulated into Hollow Carbon Nanospindles as Sulfur Host for Lithium Sulfur Batteries Dongjiu Xie, Shilin Mei, Zdravko Kochovski, and Yan Lu

AM5 - Impact of Nanoparticles' Surface Properties on their Physico-Chemical Behavior in Pickering Emulsions Sebastian Stock, Annika Schlander, Dmitrij Stehl, Ariane Weber, Sandra Forg, Reinhard Schomäcker, Markus Gallei, Regine von Klitzing

AM6 - Flocculation and delayed sedimentation induced by osmotic effect in polymer free aqueous suspensions T. Sobisch, and D. Lerche

AM7 - Effect of plasma modification on metal oxide nanoparticles - core shell structures for better and similar dispersibility – evaluation by Hansen dispersibility parameter T. Sobisch, L. Rodriguez, D. Lerche, C. Vandenabeele, A. Usoltseva and S. Lucas

AM8 - Biodegradable Polymer Foams via Foamed Emulsions M. Dabrowski, S. Varytimiadou, C. Stubenrauch

AM9 - Mussel-inspired stimuli-responsive PNIPAM-microgels Sandra Forg and Regine von Klitzing

AM10 - Colloidal Micro- and Nanopropellers for Actuation through Biological Media Tian Qiu, Florian Ralf Peter, Mariana Alarcón-Correa, Vincent Mauricio Kadiri, Zhiguang Wu, Debora Walker, Cornelia Miksch, and Peer Fischer

AM11 - Swimming Direction of Active Colloids as a Function of pH Nikhilesh Murty , Dhruv Singh and Peer Fischer

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Self - Assembly

SA1 – Sodium dodecylsulfate hydrolysis: Influence on the structure and rheological behavior of SDS-pDADMAC polyelectrolyte surfactant complexes (PESC) Olga Kuzminskaya, Ingo Hoffmann, Daniel Clemens, Michael Gradzielski,

SA2 - Syntheses and Characterization of Hydrophobically Modified

Polyacrylate Containing Block Copolymers

Özge Azeri, Dennis Schönfeld, Anja F. Hörmann, Laurence Noirez, Michael

Gradzielski

SA3 - From Regular Solutions to Structured Microemulsions: Critical

Fluctuations versus Amphiphilic Film Formation

Shih-Yu Tseng, Ulf Olsson, Reinhard Strey, Yun Liu, and Thomas Sottmann

SA4 - Influence of Chemical Structure and Architecture on Self-Assembly

of Thermo-responsive Amphiphilic Block Copolymers

Michelle Hechenbichler, Michael Gradzielski, Cristiane Henschel, André Laschewsky,

Benjamin von Lospichl and Albert Prause

SA5 - Self-Assembled Phage-Based Colloids for High Localized Enzymatic

Activity

Mariana Alarcón-Correa, Jan-Philipp Günther, Jonas Troll, Vincent Mauricio Kadiri,

Joachim Bill, Peer Fischer and Dirk Rothenstein

SA6 - Chemically powered colloids that self-assemble

Tingting Yu, Prabha Chuphal, Snigdha Thakur, Shang Yik Reigh, Dhruv P. Singh,

and Peer Fischer

Surfactants & Polymers SP1 - How promoting and breaking of intersurfactant H-bonds impact on foam stability Tamara Schad, Natalie Preisig, Leandro Jacomine, Romain Bordes, Cosima Stubenrauch

SP2 - Understanding interactions in non-aqueous thin liquid films Tetiana Orlova, Robin Bollache, Pierre Muller, Patrick Kekicheff, Natalie Preisig, Cosima Stubenrauch and Wiebke Drenckhan

SP3 - Foam film properties of NaPSS/C14TAB-mixtures: Influence of added Salt Kevin Gräff, Larissa Braun, Regine von Klitzing

SP4 - A combined Surface Tension / Neutron Reflectometry study of the salt impact on oppositely charged Polyelectrolyte/Surfactant-mixtures L. Braun and Regine v. Klitzing

SP5 - Memory effects in polymer brushes showing co-nonsolvency effects Simon Schubotz, Petra Uhlmann, Andreas Fery, Günter K. Auernhammer

SP6 - Influence of charges on the behavior of microgels at oil-water interfaces Maximilian M. Schmidt, Steffen Bochenek, Walter Richtering

SP7 - Controlling the collapse of microgels in confinement by adsorption process M. Friederike Schulte, Andrea Scotti, Monia Brugnoni, Steffen Bochenek,Ahmed Mourran, Walter Richtering

SP8 - Pressure Dependent Structural Evolution of Poly(N-isopropylacrylamide) Mesoglobules above Cloud Point Geethu P. Meledam, Bart-Jan Niebuur, Vitaliy Pipich, Marie-Sousai Appavou, Alfons Schulte, and Christine M. Papadakis

SP9 - Thermal Behavior and Cononsolvency of the Amphiphilic Diblock Copolymers PMMA-b-PNIPAM and PMMA-b-PNIPMAM in Aqueous Solution Chia-Hsin Ko, Cristiane Henschel, Lester C. Barnsley, Jia-Jhen Kang, André Laschewsky, Peter Müller-Buschbaum, Christine M. Papadakis

SP10 - Transparent Microparticles in Water/Sucrose Solution Payam Payamyar

SP11 - Structural investigation on PTX-loaded poly(2-oxazoline) molecular brushes Jia-Jhen Kang, Dan Gieseler, Lester C. Barnsley, Rainer Jordan and Christine M. Papadakis

SP12 - Round-robin test of a surface-modified polystyrene particle suspension based negatively charged zeta potential control Dr. Kyriakos A. Eslahian

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Plenary and Award Lectures

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PL1 - Emulsion stability in systems with ultralow oil-water interfacial tension.

Dominque Langevin Laboratoire de Physique-des Solides, Université Paris Sud

Emulsion stability has been the subject of many studies over the years. There are however still many open questions: for instance, we are far from understanding how two emulsion drops coalesce. Correlations with interfacial rheology, and in particular with the interfacial elastic (dilatational) modulus E are frequently observed.

In this presentation, I will take the example of systems with very low oil-water interfacial tensions, able to form microemulsions coexisting with excess oil and/or water. These systems are called Winsor systems and are of interest for tertiary oil recovery and soil remediation. When agitated, they form emulsions with extremely different stability: good for two-phase systems and poor for three-phase ones. The difference remained unexplained, mainly because there were no methods able to measure the modulus E for interfaces of low tension.

In collaboration with the group of Jean-Louis Salager in Venezuela, we have used a new method to measure this modulus, the oscillating spinning drop technique. We have shown that, as the interfacial tension, the modulus is minimum in the three-phase domain. This result allowed us to propose an explanation for the extremely important variation of emulsion stability. I will present the data and the explanation and conclude with remarks concerning the related problem of demulsifiers

Reference: Marquez, R.; Forgiarini, A. M.; Langevin, D.; Salager, J.-L., Instability of Emulsions Made with Surfactant–Oil–Water Systems at Optimum Formulation with Ultralow Interfacial Tension. Langmuir 2018, 34, 9252.

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PL2 - Group formation and cohesion of active particles with visual perception-dependent motility

Clemens Bechinger Fachbereich Physik, Universität Konstanz

Group formation is frequently observed in living systems. It typically results from a delicate balance of repulsive, aligning, and attractive mutual interactions. Here, we show that a motility change of individuals in response to their visual perception of the group is sufficient to induce formation and cohesion of stable groups. Experimentally, this is demonstrated using active particles whose motility is controlled by an external feedback-loop. We demonstrate that when individuals have a relatively narrow field of view, they gather into strongly cohesive groups while remaining highly motile. For larger field of views, cohesion can only be achieved by lowering the response threshold. Our results are supported by simulations with point-like particles, which confirms that active reorientations are not necessary to ensure cohesion, as often assumed. We expect this group formation mechanism to be relevant not only for the self-organization of living systems, but also for the design of autonomous self-propelling systems.

1. F. Lavergne, H. Wendehenne, T. Bäuerle, C. Bechinger Science 364, 70-74 (2019).2. T. Bäuerle, A. Fischer, T. Speck, C. Bechinger, Nat. Comm. 9, 3232 (2018).

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PL3 - Interplay of bubbles and drops in foamed emulsions

Anniina Salonen

Laboratoire de Physique des Solides, Université Paris Sud

The reason oil is added to foam is often to destabilise foam, as the oil acts as an antifoam promoting

bubble coalescence. However, well-stabilised oil drops can be harmless to foam stability, and at high

concentrations drops can considerably increase foam lifetimes. This is why mixtures of oil drops and

gas bubbles are encountered daily in food or cosmetics products, or during material processing.

Despite the number of applications, many questions remain on the properties of such mixtures.

We have explored the influence of oil in water emulsions on the stability and rheology of foams, an

image of such a foamed emulsion is shown below. We have followed the flow of emulsion through the

foam channels to see how it phase separates during creaming. The influence of emulsion on the

stability of the foam evolves in time as the flow slows down and the emulsion concentrates. The

emulsion slows down drainage leading to more stable foams, before causing foam collapse. We also

show how mixing elastic emulsions with bubbles allows to finely modulate the mechanical properties

of the systems.

Figure 1 An image of a foamed emulsion under a fluorescence microscope (oil drops in red).

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PL4 - From colloidal solution chemistry to greener product formulations

Werner Kunz

Institute of Physical and Theoretical Chemistry, University of Regensburg, Germany Werner.Kunz@ur.de

Many people work in the field of colloid and interface science, others on the topic of solution chemistry. We try to do both and to combine our thus gained knowledge to make better formulation products. Better essentially means “greener” or more efficient or both. To this purpose, we consider solubilisers (hydrotropes), salting-in and -out effects, the behaviour of polymers in solutions, new types of surfactants, enzymatic reactions, structuring and self-organisation in liquids and at their interfaces etc. and especially synergistic effects. In the present contribution, I will shortly focus on the following concepts and visions: - the use of specific ion effects to make better formulations.- the possible renaissance of soaps in formulation.- my personal point of view of “green solvents” including Ionic Liquids and Deep Eutectic Solvents,

and in particular Ionic Liquids based on our COMPLET concept with Akypos™ as anions.- the use of bio-based surfactants and of biopolymers.- how to make micellar-like structures without surfactants or polymers.

Weak pseudo-microemulsion structuring in mixtures of water and two alcohols without surfactant and at different mixing ratios. The resulting “interfaces” are ultra-flexible and mobile and can be used to improve mass transfer, reaction kinetics and separation processes. The pictures show results from MD simulations in agreement with SAXS and SANS data. [T. Lopian, S. Schöttl, S. Prévost, S. Pellet-Rostaing, D. Horinek, W. Kunz, and T. Zemb, Morphologies observed in ultra-flexible microemulsions with and without the presence of a strong acid, ACS Central Science 2 (2016) 467-475.]

References:

K. Häckl, W. Kunz, Some aspects of green solvents, Comptes Rendus de l’Académie des Sciences (France) Chimie, 21 (2018) 572-580. G. Grundl, M. Müller, D. Touraud, W. Kunz, Salting-out and salting-in effects of organic compounds, The Journal of Molecular Liquids 236 (2017) 368-375. S. Wolfrum, D. Touraud, W. Kunz, A Renaissance of Soaps? – How to make clear and stable solutions at neutral pH, Advances in Colloid and Interface Science 236 (2016) 28-42. W. Kunz, K. Holmberg, T. Zemb, Hydrotropes, Current Opinion in Colloid and Interface Science 22 (2016) 99-1.S. Krickl, T.Buchecker, A. U. Meyer, I. Grillo, D. Touraud, P. Bauduin, B. König, A. Pfitzner, W. Kunz, A systematic study of the influence of mesoscale structuring on the kinetics of a chemical reaction, Physical Chemistry Chemical Physics 19 (2017) 23773-23780. E. Müller, L. Zahnweh, B. Estrine, O. Zech, C. Allolio, J. Heilmann, W. Kunz, Oligoether Carboxylate Counterions: An Innovative Way Towards Surfactant Ionic Liquids, Journal of Molecular Liquids 251 (2018) 61-69. Y. Duan, A. Freyburger, W. Kunz, C. Zollfrank, Cellulose and chitin composite materials from a green solvent, Carbohydrate Polymers 192 (2018) 159-165. H. Garcia, R. Ferreira, C. Martins, A. F. Sousa, C. S. R. Freire, A. J. D. Silvestre, W. Kunz, L. P. N. Rebelo, C. da Silva Pereira,Ex-situ reconstitution of the plant biopolyester suberin as a film, Biomacromolecules 15(5) (2014) 1806-1813.

24

PL5 - Classical phenomena to new use: Magnetism and capillarity in the making of responsive and active colloidal structures Orlin D. Velev Department of Chemical and Biomolecular Engineering, North Carolina State University,

Raleigh, NC 27695, USA

odvelev@ncsu.edu; http://crystal.che.ncsu.edu/

The directed assembly of colloidal microparticles can provide efficient means of making

sophisticated active structures and materials. The key to these structures is the design of

directional interactions and of flexible inter-particle bonds. This can be achieved by using

magnetic interactions (weak on the colloidal scale) and capillary forces (usually strong). We will

discuss how magnetic fields in combination with capillarity can be used to make novel classes of

flexible, responsive and dynamically reconfigurable colloidal structures. In the first part of the

talk, we will discuss how the magnetic polarization patterns on metallodielectric microcubes lead

to multidirectional interactions and assembly of reconfigurable microclusters. These sequence-

encoded clusters can be reversibly actuated by magnetic fields and can be designed to be self-

motile in non-Newtonian media. In the second part of the talk we will describe three new types

of multiphasic capillary gels made from particles bound by liquid bridges. The first gel system is

composed of filaments from magnetically responsive iron oxide nanoparticles suspended in

water-oil systems. The nanocapillary binding results in ultra-high filament flexibility. The

second system is a toolbox of making magneto-capillary gels made of PDMS beads with

embedded magnetic nanoparticle chains, which may also be bound by capillarity. The third

multiphasic system is a new class of 3D printing inks consisting of PDMS microbeads, liquid

PDMS and water. Owing to the capillary binding, such Homocomposite Thixotropic Pastes

(HTPs) can be extruded and shaped on a 3D printer. The curing of the liquid bridges in the HTPs

results in remarkably elastic and flexible porous silicone structures. The method makes possible

the fabrication of soft architectures that could act as reconfigurable “magneto-capillary” 2D

auxetic materials, soft actuators, and microtools for interfacial studies.

25

PL6 - Elaboration of double emulsion-based polymeric capsules

for fragrance retention

Margot Stasse1,2, Valérie Héroguez2 and Véronique Schmitt3

1 Centre de Recherche Paul Pascal UMR 5031 CNRS University of Bordeaux France. 2 Laboratoire de Chimie des Polymères Organiques UMR 5629 CNRS University of Bordeaux

France.

We aim at encapsulating fragrances made of a variety of lipophilic species to slow down their

diffusion. Our strategy is to develop capsules by polymerizing the water intermediate phase of an

oil-in-water-in-oil double emulsion. In other terms, our system consists in a direct emulsion of

fragrance (O1) in a water phase (W) containing monomer, initiator and crosslinker. To obtain the

double emulsion, this direct emulsion, stabilized by a hydrophilic surfactant, is itself dispersed in an

external lipophilic solvent used in perfumery (O2) and stabilized by a lipophilic surfactant.

Polymerization of the intermediate water phase aims at obtaining a 3D network. Differently from

nowadays proposed capsules, this strategy allows polymerization to only take place in the water

phase rather in the phase containing the fragrance. Moreover the obtained 3D network is supposed

to play the role of an effective barrier limiting the diffusion of the inner lipophilic species towards

either the external solvent or air.

Such an approach implies the combination of a formulation step to elaborate the double emulsion

using two antagonistic surfactants, a hydrophilic and a lipophilic one, and of the polymerization of

the intermediate phase. Insertion of the polymerizable species in the double emulsion shall not

destabilize it. Some monomers exhibiting interfacial affinity and interfering with the formulation of

the double emulsion have to be avoided. By varying the nature of the monomers, the initiator to

monomer ratio and the crosslinker to monomer ratio, capsules with high encapsulation efficiencies

and with various mechanical properties have been obtained.

a b

Figure 1. a) optical microscopy picture of a fragrance-in-water-in perfumery oil double emulsion

and b) scanning electron microscopy of a capsule obtained from a double emulsion.

[1] M Stasse “Encapsulation of active lipophilic species by double emulsions” PhD ThesisUniversité de Bordeaux 2018.

26

PL7 - Self-assembly of flexible colloidal structures

Daniela J. Kraft1

1 Soft Matter Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, PO Box 9504,

2300 RA Leiden, The Netherlands Affiliation of the first author, including Department/Institution,

City and Country

Many functional (bio-)molecules possess structural flexibility which provides functional properties

and a more complex phase behavior. For example, different conformations may enhance or inhibit a

protein’s activity in allosteric regulation or enable the catalytic activity of enzymes. Colloidal

structures currently lack this property, restricting their use as building blocks in reconfigurable

materials and model systems.

In this talk, I will introduce colloidal particles with surface-mobile DNA linkers [1,2] – so called

colloidal joints [3]- that enable the formation of strong and specific hinging bonds. I will describe

how this bond mobility affects their diffusive and self-assembly behavior and demonstrate the

assembly of a variety of flexible structures. In particular, I will discuss the formation of colloidal

molecules with tunable flexibility and shape in high-yields. These novel colloidal building blocks

give access to a new class of materials with great potential in shape-shifting systems, actuators and

colloidal robots.

[1] Rinaldin*,Verweij* et al., Soft Matter, 15 2019, 1345-1360

[2] van der Meulen, Leunissen, JACS, 135 (40) 2013, 15129-15134

[3] Chakraborty et al., Nanoscale, vol 10 2018, 3541

27

PL8 - Hybrid colloids as printable materials

Tobias Kraus1,2

1INM – Leibniz-Institute for New Materials, Campus D2 2, 66123 Saarbrücken 2Kolloid- und Grenzflächenchemie, Universität des Saarlandes, 66123 Saarbrücken

Hybrid materials that combine mesoscale inorganic and organic components can unite

seemingly contradictory properties. I will highlight new materials that are mechanically soft,

optically transparent, and electrically conductive; we investigate their use in ergonomic

human-machine-interfaces and in soft robotics. The materials are processed at low

temperatures and have properties that strongly depend on the geometry of their colloid-

derived components.

My talk will focus on “inks” – colloidal precursors of hybrid materials. We prepare

dispersions of particles with inorganic cores and soft organic shells that can be printed to form

functional materials immediately or upon soft sintering. I will discuss the inkjet printing of

metal nanoparticles with conductive polymer shells to obtain 2-2.5 D structures that become

electrically conductive immediately upon drying. Other inks are suitable for the imprinting of

transparent sub-100 nm lines, and I will show how ultrathin nanowires spontaneously bundle

and ensure percolation.

Synthesis, formulation, and printing of inks entail interesting colloidal challenges. I will

discuss how the agglomeration concentration of apolar dispersions and the final spacing

between particles can be controlled by tuning the ratio between inorganic and organic

components. We observe agglomeration using evaporating droplets of dispersion that hang in

the beam of a Small-Angle X-ray Scattering setup. This lets us to probe the concentration-

dependent stability of nanoparticles at very high concentrations with sufficient precision to

provide new insight into molecular ligand-solvent interactions, and to predict when the

particles will agglomerate during printing.

Important properties of hybrid materials are dominated by internal interfaces that derive from

their colloidal precursors. I will show how we link the molecular structure of hybrid particles

to the structure of the resulting material and, eventually, its properties. Fundamental colloidal

results thus lead to new material questions: How stretchable can we make an electrically

conductive, hybrid material? How precise can the assembly of particles be, how precise does

it have for certain properties, and does this enable new functionalities?

28

PL9 - Particle Aggregation Graham Award Lecture

Michal Borkovec

Department of Inorganic and Analytical Chemistry, University of Geneva, Sciences II,

Quai Ernest-Ansermet 30, 1205 Geneva, Switzerland

Email: michal.borkovec@unige.ch

The breakthrough of Derjaguin, Landau, Verwey, and Overbeek (DLVO) was the derivation of the Schulze-Hardy rule from first principles. This rule states that multivalent ions are more effective to induce colloidal particle aggregation than monovalent ones, whereby the effectiveness increases with the 6th power of ionic valence. Today we know, however, that this derivation makes incorrect assumptions. Firstly, high surface charge densities are assumed, while these densities are typically low. Secondly, symmetric electrolytes are considered, but these typically are poorly soluble. Therefore, the better soluble asymmetric electrolytes are normally being used.

I will first focus on these seeming contradictions. Studies of the same particles with time-resolved light scattering studies and direct force measurements permit to disentangle the situation. Systematic analysis of colloidal aggregation reveals the fundamental differences between asymmetric electrolytes, where the multivalent ions represent counter-ions or co-ions. For the latter situation, I will in fact propose a new rule, the inverse Schulze-Hardy rule.

While the first part of the talk focuses on the commonly investigated homoaggregation, the second part will address the poorly investigated heteroaggregation. In contrast to homoaggregation, where aggregates are being formed from the same (or very similar) particles, different types of particles are involved in heteroaggegation. A difficulty in the experimental investigation of these processes is that even in the early stages different types of aggregates form. I will show that time-resolved and angle-dependent light scattering permits to disentangle contributions from the different aggregates, whereby the one from heteroaggregation can be extracted. This scattering technique permits to study heteroaggregation processes routinely, and such studies can be used to identify the relevant scenarios. Thereby, the key role of charge regulation in heteroaggregation processes will become apparent.

29

PL10 - Out of the gel and into the equilibrium liquid crystal: how fractionation

of cellulose nanocrystals transforms phase diagram, cholesteric helix

formation and tactoid behavior

Camila Honorato Rios and Jan Lagerwall.

University of Luxembourg, Physics and Materials Science Research Unit,

162a Avenue de la Faiencerie, L-1511 Luxembourg, Grand Duchy of Luxembourg

Aqueous suspensions of cellulose nanocrystals (CNCs) constitute a fascinating model colloid for

fundamental physics research, while at the same time attracting rapidly increasing interest from in-

dustry. The latter is primarily due to the facts that CNCs are sustainably produced bio-derived nano-

rods that can be processed in water, are transparent and exhibit highly attractive mechanical proper-

ties, and that their suspensions can be dried into films that exhibit iridescent colors thanks to a heli-

cal structure with sub-micrometer period. This structure has its origin in the ability of CNC suspen-

sions to form a cholesteric liquid crystal phase beyond a threshold particle volume fraction that de-

pends on the rod aspect ratio. Regrettably, pristine CNC suspensions are notoriously disperse in rod

length, hampering technical development as well as the study of CNC suspensions from a funda-

mental physics point of view. The dispersity means that pristine CNC suspensions leave equilib-

rium behavior and enter a gel state before the entire system has become liquid crystalline, it tends to

produce less uniform colors in dried films, and it renders an investigation of the impact of rod

length on key properties like cholesteric helix pitch, phase diagram and tactoid characteristics

impossible.

In this talk I will demonstrate that the solution is provided by the CNC suspension itself, through its

ability to phase separate into liquid crystal and isotropic phases, respectively [1]. Classical Onsager

theory predicts that the liquid crystal fraction contains primarily long rods whereas the shortest rods

stay in the isotropic fraction even at high particle content. By separating these phases following one

of three protocols developed in our lab, we obtain CNC suspension with much reduced dispersity,

some containing the longest rods of the original sample, others having the shortest rods. Having ac-

cess to these fractions removes a major obstacle in the research on CNC suspensions, allowing us to

significantly expand the liquid crystal phase diagram and answer a number of key questions relating

to the colloidal behavior of CNC suspensions. We find that the rod length impacts neither the onset

of gelation nor the cholesteric helix pitch, whereas both parameters are critically affected by the

counter ions, and that tactoids never merge and therefore lead to non-uniform dried films if the

CNCs are too short. These and other observations will be explained in the talk. [2]

[1] C. Honorato Rios et al., NPG Asia Materials, 10 (2018) pp. 455-465.

[2] The authors acknowledge funding from the Fonds National de la Recherche Luxembourg,

project MISONANCE, grant code C14/MS/8331546.

30

PL11 - Compartmentalized Colloidal Particles

André H. Gröschel

Physical Chemistry and Center for Nanointegration Duisburg-Essen (CENIDE), University of

Duisburg-Essen, 47057 Duisburg, Germany.

Colloidal particles in the range of few nanometers to several micrometers are ubiquitous in nature,

science and technology. While wet chemical synthesis has mastered the formation of isotropic

particles with near-monodisperse size distribution, concepts towards more complex particles are

currently under rapid development. In nature, bioparticles are often grown from smaller building

blocks and result in higher structural complexity regarding shape, surface and inner structure. The

self-assembly of block copolymers to nano- and microparticles follows this principle in a simplistic

manner and has emerged as a versatile tool to generate particles with ordered porous lattices,

compartments, and patchiness [1,2].

In this contribution, I present recent work from my group in the field of block copolymer self-

assembly in concentrated solutions and in the confinement of nanoemulsion droplets (Fig. 1) [3–6].

Under these conditions, block copolymers form microparticles with unusual shapes and inner

structure through a competition of microphase separation and interfacial tensions. The assembly of

amphiphilic AB diblock copolymers yields porous cubosomes and hexosomes, whereas ABC

triblock terpolymers give access to a large variety of multicompartment microparticles. Porous

microparticles are useful for capture and release of cargo and are currently explored for energy

storage and conversion. Terpolymer-based microparticles on the other hand, serve as templates for

the formation of Janus nanoparticles including Janus rings, cups, perforated discs and discs with

tunable stiffness. We currently expand our efforts to control size, dispersity and inner structure of

the microparticles, while the soft Janus nanoparticles are tested for their properties in interfacial

stabilization, cell internalization, directional assembly and locomotion [7].

Figure 1. Confinement assembly of block copolymers to block copolymer hexosomes and

multicompartment microparticles.

[1] Z. Lin et al., Angew. Chemie Int. Ed. 2017, 56, 7135–7140.

[2] J. M. Shin, Y. Kim, H. Yun, G. R. Yi, B. J. Kim, ACS Nano 2017, 11, 2133–2142.

[3] X. Qiang, A. Steinhaus, C. Chen, R. Chakroun, A. H. Gröschel, Angew. Chemie Int. Ed. 2019,

58, 7122–7126.

[4] A. Steinhaus, R. Chakroun, M. Müllner, T.-L. Nghiem, M. Hildebrandt, A. H. Gröschel, ACS

Nano 2019, acsnano.8b09546.

[5] A. Steinhaus, T. Pelras, R. Chakroun, A. H. Gröschel, M. Müllner, Macromol. Rapid Commun.

2018, 39, 1800177.

[6] A. H. Gröschel, A. Walther, Angew. Chemie Int. Ed. 2017, 56, 10992–10994.

[7] A.H.G. acknowledges funding from German Research Foundation (DFG) through the Emmy

Noether Program (No. 376920678) and from Evonik industries through a Junior-Professorship.

31

PL12 - Oil Foams Stabilised by Surfactant or Fat Crystals

Bernard P. Binks, Emma J. Garvey, Yu Liu and Ioannis Marinopoulos

Department of Chemistry and Biochemistry, University of Hull, Hull. HU6 7RX. UK

b.p.binks@hull.ac.uk

The literature on oil foams (air-in-oil) is quite scant and the area is much less studied

compared with aqueous foams despite their occurrence in industrial situations. Although some

reports show the use of special surfactants (normally fluorocarbon-based) as oil foam

stabilisers, the long-term stabilization of oil foams remains a challenge. Here, we describe the

stabilization and properties of sunflower oil (containing long chain triglycerides) foams

stabilized by adsorbed crystals of surfactant. An oil solution of myristic acid at high

temperature is controllably cooled until plate-like crystals are formed below the solubility limit.

These oil dispersions can then be aerated to produce oil foams in which air bubbles are coated

with crystals and in which excess crystals form a network in oil to thicken the continuous phase.

The foams are ultra-stable showing no sign of coalescence or disproportionation over at least

a year. The oil foam is stimulus-responsive whereby warming it progressively induces foam

collapse on approaching the melting point of the crystals.

In taking this idea further, we demonstrate the stabilization of vegetable oils containing

a mixture of medium or long chain triglycerides in the absence of added foaming agent by

controlling the temperature. Triglycerides of high melting point selectively crystallise in a

continuous phase of triglycerides of low melting point; these crystals coat air bubbles in the

foam after aeration. We suggest the likely orientation of triglyceride crystals at the oil-air

surface of bubbles.

32

Special Lectures

33

34

SL1 - Entrainment dynamic of anisometric particles in an active bath

Florian von Rülling and Alexey Eremin

1 Otto von Guericke University, Institute of Physics, Magdeburg, Germany

Enhanced diffusion of passive tracers immersed in active fluids exhibit universal features of active

matter and has been extensively studied in recent years [1,2]. Interactions with active swimmers have

been found to affect the probability distribution functions of translational and translational

displacements of passive particles. In case of pusher-type swimmers it may even lead to the inversion

of the diffusion anisotropy in case of the anisometric passive particles.

We report experimental studies on the active motion of puller-type microswimmers Chlamydomonas

reinhardtii and the entrainment of the diffusion of complex passive particles in thin capillaries.

Chlamydomonas reinhardtii, self-propelled unicellular alga, swims in the regime of low Reynolds

number due to its flagellar motion breaking time-reversal symmetry. Having an eyespot, the alga

shows phototactic behaviour. Employing a particle tracking algorithm and video microscopy, we

explore the enhancement of the diffusion of the sphere- and rod-shaped particles by swimming algae.

The diffusive transport of elongated passive particles with dimensions comparable to the size of

Chlamydomonas reinhardtii is enhanced in the collective hydrodynamic far field generated by the

microswimmers. For small concentrations of algae, the trajectories of passive particles resemble

random walks with Lévy-flights, the latter being a consequence of rare close encounters of individual

algae and passive particles. Such events are more frequent for higher swimmer concentrations. At

higher concentration the active swimmers self-organize into crystal-like 2D structures considerably

suppressing the diffusion of passive particles.

[1] Y. Peng, L. Lai, Y.-S. Tai, K. Zhang, X. Xu, and X. Cheng, “Diffusion of Ellipsoids inBacterial Suspensions,” Phys. Rev. Lett., vol. 116, no. 6, pp. 068303–5, (2016)

[2] K. C. Leptos, J. S. Guasto, J. P. Gollub, A. I. Pesci, and R. E. Goldstein, “Dynamics ofEnhanced Tracer Diffusion in Suspensions of Swimming Eukaryotic Microorganisms,” Phys. Rev.

Lett., 103, 198103, (2009).

35

SL2 - The Impact of Brush/Water Interface on the self-propulsion of Janus

Particles

Mojdeh Heidari1, Franziska Jakob1 and Regine von Klitzing1

1 Soft Matter at Interfaces, Department of Physics, TU Darmstadt, Darmstadt, Germany

We explore the 2D self-propulsion of single Au-PS Janus particle between two brush functionalized

glass substrates. The autonomous motion of the particle is achieved under wide parallel laser beam

illumination (λ=532 nm) with various intensities. In this case, thermophoresis is the driving

mechanism underlying the self-propulsion of particles. We vary the chain length of the brush layer,

hence the thermo-osmotic flow at the substrate/water interface alters [1], which subsequently

influences the active motion of particles. We characterized the brush substrates with various

methods, including Ellipsometry, AFM, etc. Surprisingly, the self-propulsion of particles is

enhanced near brush functionalized substrate in comparison to neat substrate. Variation of the brush

chain length leads to a maximum at a certain chain length which indicates two counteracting effects.

They will be discussed in the presentation.

[1] A Würger, Rep. Prog. Phys. 73 (2010) 126601

[2] Janus particles were a kind gift from the group of Prof. Cichos and were synthesized by

Santiago Muinos Landin

36

SL3 - Rotation of a thermo-chemically active colloid with random surface

activity around the center of an optical trap

Mihail N. Popescu1

1 Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart, GERMANY

The experimental study in Ref. [1] involves optically trapped silica particles, which contain iron-

oxide inclusions and are immersed in a critical binary mixture liquid at a temperature below the

critical point. It has been observed that upon increasing the laser power of the optical trap above a

certain threshold, a local demixing of the solution – due to the heating of the particle because of the

light absorbtion by the iron-oxide inclusions – occurs near the particle. This is correlated with a

displacement of the particle away from the center of the trap and, surprisingly, a stable systematic

orbiting around the center of the trap (basically a constant velocity circular motion). This finding

was accurately captured by Brownian dynamics simulations that invoked some effective forces and

torques on the particle, which were attributed to self-diffusiophoretic behavior [1].

In this contribution, I use a simple model of an active particle [2,3] to show that indeed in the set-up

above a self-diffusiophoretic mechanism may give rise to translations and rotations of the particle

compatible with the experimental observations. These components of the motion are calculated as

functionals of the experimentally measurable distribution G(r) of the absorbing inclusions (with

G(r) = 1 on absorbing center and zero otherwise [4]. This systematic analysis provides the means

for understanding which features of the distribution G(r) determine the behavior of lock-in in a

steady-state orbiting around the center of the trap. Such predictions about the spatial distribution of

the absorbing centers provide the means for direct experimental testing of the theoretical model;

furthermore, they could translate into designing rules for the particle and optical trap ensemble in

order to achieve pre-selected patterns of motion.

[1] F. Schmidt et al., Phys. Rev. Lett. 120, 068004 (2018).

[2] R. Golestanian, T.B. Liverpool, and A. Ajdari, New J. Phys. 9, 126 (2007).

[3] M.N. Popescu et al, Eur. Phys. J. E 31, 351 (2010).

[4] M.N. Popescu, in preparation (2019).

37

SL4 - Influence of Surfactant Chain Length on the Viscosity in Polyelectrolyte /

Surfactant Complexes

Giuseppe Rosario Del Sorbo1,2, Ingo Hoffmann2 and Emanuel Schneck1

1 Max-Planck-Institut für Kolloid und Grenzflächenforschung, Am Mühlenberg 1, 14476 Potsdam,

Germany 2 Institut Laue-Langevin, 71 av. des Martyrs, 38042 Grenoble Cedex 9, France

Oppositely charged polyelectrolyte (PE) surfactant complexes (PESCs) show rich self-aggregation

behaviour varying over a large size range. In addition, they have many applications in cosmetics

detergency and drug delivery [1,2]. Some of these mixtures show a remarkable increase in viscosity

when adding surfactant to a semi dilute PE solution with otherwise low viscosity, such that the there

still is a slight excess of PE charges. Previously, it has been established that for mixtures of the

cationically modified hydroxyethyl cellulose JR 400 and the anionic surfactant sodium dodecyl

sulphate (SDS), this increase in viscosity is due to the formation of mixed rodlike aggregates which

act as cross-links between PE chains [3].

Here, we investigate the influence of the surfactant chain length on the rheological properties of the

solutions and find a drastic decrease in viscosity with decreasing surfactant chain length. This

change of the macroscopic properties is related to a change in mesoscopic structure and dynamics,

which are probed using small angle neutron scattering (SANS) and neutron spin-echo spectroscopy

(NSE). These experimental findings are complemented by molecular dynamics (MD) simulations.

The combination of these different methods provides a detailed picture of the mesoscopic origins of

the macroscopically observed increase in the viscosity of oppositely charged PESCs.

[1] M Gradzielski and I Hoffmann, Curr Opin Colloid Interface Sci 35 (2018), p. 124.

[2] L Chiappisi, I Hoffmann and M Gradzielski, Soft Matter 9 (2013), p. 3896.

[3] I Hoffmann et al., J Chem Phys 143, (2015), p. 074902.

38

SL5 - Microemulsions at planar surfaces with and without flow

Henrich Frielinghaus1

1 Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science JCNS at MLZ,

Lichtenbergstrasse 1, D-85747 Garching, Germany

Microemulsions consist of water, oil and surfactant. Although thermodynamically stable, domains

of pure water and oil are formed on nanometer length scales and a surfactant film in between that

are ideally observable by small angle scattering experiments. The bicontinuous microemulsion

displays a sponge structure that forms when equal volumes of water and oil are mixed. Being

exposed to hydrophilic planar surfaces, a lamellar order is found in the vicinity to the solid-liquid

interface. The typical depth of the lamellae is 40 to 60nm, i.e. 4 to 6 perfect domains [1,2], before

the perforations describe the decay to the bicontinuous phase. The membrane modes observed by

neutron spin echo spectroscopy under grazing incidence are faster at the interface than in bulk [3].

This is an evidence for the lubrication effect, a facilitated flow of the lamellae along the interface.

Employing clay platelets, the same effect could be observed in a bulk sample [4]. Furthermore, at

smaller platelet diameters, the favorable modes of the lamellae were cut, and the overall dynamics

slowed down similar to the bulk. Thus, the perfection of modes at the interface is connected to the

platelet diameter. At rather high flow rates, the perforated transition region was reduced in size,

while the perfect lamellae were persistent [2]. In macroscopic rheology experiments (Fig.1 left), the

microemulsion with rather large clay platelets showed evidence for the lubrication effect on

macroscopic scales, while at lower clay dimensions the viscosity was extraordinarily high [5] (Fig.1

right). Motivated by this effect, the rheology of crude oils with large clay platelets showed

decreased viscosities at low temperatures (below 0°C). The dynamic asymmetry of the aromatic and

aliphatic portions and the lamellar alignment of the domains may explain these findings.

Figure 1. (left) A rheometer in tangential geometry in a SANS instrument. (right) Complex

viscosities of clay dispersions in water and microemulsion with varying platelet diameter.

[1] M. Kerscher, P. Busch, S. Mattauch, H. Frielinghaus, D. Richter, M. Belushkin, G. Gompper,

Phys. Rev. E 83 (2011) p. 030401(R).

[2] F. Lipfert, M. Kerscher, S. Mattauch, H. Frielinghaus, J. Coll. Interf. Sci. 534 (2019) p. 31.

[3] H. Frielinghaus, M. Kerscher, O. Holderer, M. Monkenbusch, D. Richter, Phys. Rev. E 85

(2012) p. 041408.

[4] F. Lipfert, O. Holderer, H. Frielinghaus, M.S. Appavou, C. Do, M. Ohl, D. Richter, Nanoscale 7

(2015) p. 2578.

[5] M. Gvaramia, G. Mangiapia, V. Pipich, M.S. Appavou, G. Gompper, S. Jaksch, O. Holderer,

M.D. Rukhadze, H. Frielinghaus, arXiv:1709.05198 (2017).

39

SL6 - Structure and Phase Behaviour of a New Type of CO2-Containing

Dodecylethoxylate Surfactants

Vivian J. Spiering1, Michelle Tupinamba Lima2, Reinhard Schomäcker2 and Michael Gradzielski1 1Stranski-Laboratorium, Institut für Chemie, Technische Universität Berlin, Berlin, Germany2Institut für Chemie - Technische Chemie, Technische Universität Berlin, Berlin, Germany

Using CO2 as a resource in the production of materials is a viable alternative to conventional,

petroleum-based raw materials and therefore offers great potential for sustainable chemistry. This

study presents the characterization of non-ionic surfactants with different CO2 content in the

ethylene oxide (EO) head group, with respect to their self-assembly behaviour.

In this study we present the characterization of these CO2 containing surface active compounds with

respect to their colloidal properties, surface activity, and their self-assembly behavior, and this as a

function of temperature. Understanding the thermodynamic influence of the CO2 unit in the

hydrophilic headgroup on the micellization process is an essential aspect of their self-assembly

behavior. Compounds with different CO2 content and comparable hydrophobic groups like

propylene oxid (PO) are analyzed with surface tension measurement and isothermic titration

calorimetry and compared here in a systematic fashion also to their commercial alkylethoxylate

counterparts.

The CO2 unit plays an important role as an additional tuning parameter to specifically control the

surfactant properties. However the CO2-containing surfactants show similar characteristic molecular

self-assembly behaviour in aqueous solution to conventional non-ionic surfactants. The CO2 units

render the surfactants somewhat more hydrophobic, thereby lowering their CMC´s. At lower

concentrations; they form micelles, the shape of which is temperature dependent, and they possess

the properties relevant for practical applications. Interestingly, for higher CO2 content, the

surfactants lose their tendency to form liquid crystalline phases at higher concentrations, thereby

having substantially lower viscosities. The phase behavior and the micellar structure was

characterized by dynamic (DLS) and static (SLS) light scattering as well as by small angle neutron

scattering (SANS), where the data gives detailed insights into the mesoscopic organization.

These practical advantages, combined with a less environmentally damaging production method,

demonstrate that CO2-containing surface-active compounds are a viable, ‘greener’ alternative to conventional non-ionic surfactants.

Fig 1: (left) Schematic illustration of the surface activity and the self-assembly behavior and (right) the

phase behavior at higher concentrations for the CO2 surfactants.

40

SL7 - Carbon Nanofibers (CNFs) from Electrospun Polyacrylonitrile (PAN)

Nanoparticle Composites

Wael Ali1, Valbone Shabani2, Thomas Mayer-Gall1, Muhammad Saif Maqsood1,2, Jochen S.

Gutmann1,2

1 Deutsches Textilforschungszentrum Nord-West (DTNW), Krefeld, Germany 2 University of Duisburg-Essen, Physical Chemistry & CENIDE, Essen, Germany

In this work, a pioneering study on the electrical properties of composite carbon nanofibers (CNFs)

are interesting materials which usable in a wide array of applications such as electrode materials for

biosensors, lithium ion batteries, fuel cells and supercapacitors. As they offer the potential to

generate conductive systems with a high surface area and chemical inertness.

A scalable way to produce CNFs is electrospinning of polyacrylonitrile (PAN) as a precursor for

carbonization. One major problem in the production of CNFs is the carbonization as this step

typically compromises the structural integrity of the fibers unless the fibers are sufficiently

stabilized.

Using composite silver nanoparticle (AgNPs)-containing PAN solutions we demonstrate that it is

possible to electro-spin nanofibers with varying morphology and fiber diameter. The resulting fibers

were characterized by scanning electron microscopy (SEM). UV-Vis spectroscopy and dynamic

light scattering (DLS), while energy-dispersive X-ray spectroscopy (EDX) and transmission

electron microscopy (TEM) were carried out to investigate the presence as well as the average

diameter of the AgNPs. The electrical properties of the CNFs were investigated on mesoscopic

scales using CS-AFM.

In this way we are able to demonstrate that the composite CNFs feature a higher electrical

conductivity than neat CNFs and both the average diameter of the fibers and the electrical

conductivity increase with an increasing AgNP content.

[1] W. Ali, V. Shabani, M. Linke, S. Sayin, B. Gebert, S. Altinpinar, M. Hildebrandt, J. S. Gutmann

and T. Mayer-Gall RSC ADVANCES 9 (2019), 4553-4562

41

SL8 - Superspreading - Has the mystery been unraveled?

Joachim Venzmer

Evonik Nutrition & Care GmbH, Research Interfacial Technology, Essen, Germany.

Superspreading is a fascinating phenomenon that was first observed more than 20 years ago [1]

with dilute solutions of trisiloxane surfactants on hydrophobic substrates (Figure 1). It has attracted

much attention mainly for two reasons: (i) the practical benefits of the effect in agrochemical

applications and (ii) the scientific challenge to explain both the physics behind the phenomenon and

the mode of action of the surfactants. Despite the work of many groups all over the world that has

contributed significantly to the understanding of this phenomenon, the reasons why only some

trisiloxane surfactants promote superspreading, whereas others of similar chemical structure behave

more like ordinary surfactants, remained somewhat of a mystery for decades.

This presentation will cover the different approaches to explain superspreading, including the more

philosophical aspect of how to discover the truth about an – on a molecular scale – unobservable

phenomenon. Basically, there is the choice between (i) quantitative models that are in agreement

with the kinetics of superspreading, but not involving or even ignoring the chemical structures of

the surfactants, or (ii) conceptual sketches that are able to explain the phenomena encountered in the

application of trisiloxane surfactants, including the known structure/property relationships. It will

be discussed how more recent experimental findings which are not related to wetting phenomena

[3] could support one of these hypotheses.

Figure 1. Photos taken 1 minute after placing a 50 μL droplet onto polypropylene film (with a cm

scale underneath). (A) Water. (B) Non-superspreading trisiloxane surfactant (M(D’E10P2OH)M): 15

mm diameter. (C) Superspreading trisiloxane surfactant (M(D’E6P3OH)M): 70 mm diameter [2].

[1] J Venzmer, Curr. Opinion Colloid Interf. Sci. 16 (2011) p.335-343.

[2] J Venzmer in “Droplet Wetting and Evaporation”, ed. D Brutin, Elsevier 2015, p.71-84.

[3] S Sett, RP Sahu, S Sinha-Ray and AL Yarin, Langmuir 30 (2014) p.2619-2631.

42

SL9 - Monodisperse Highly Ordered Chitosan/Cellulose Nanocomposite Foams Sébastien Andrieux1, Lilian Medina2, Michael Herbst1, Lars Berglund2 and Cosima Stubenrauch1

1 Institute of Physical Chemistry, University of Stuttgart, Stuttgart, Germany 2 Department of Fiber and Polymer Technology, Wallenberg Wood Science Center, KTH Royal

Institute of Technology, Stockholm, Sweden

The physical properties of solid foams depend on their structure and relative density. Controlling

those is thus crucial to adapt their mechanical properties. Microfluidic-aided foam templating

allowed us to do so, i.e. to generate monodisperse chitosan foams [1,2]. However, foam properties

also depend on the material they are made of. In case of chitosan, the foams have poor mechanical

properties because of the low water solubility of chitosan and the correspondingly low relative

density of the solidified foams. We incorporated cellulose nanofibres into the foamed chitosan

solutions to strengthen the mechanical properties of the solid foam, according to what had been

done on non-foamed chitosan/CNF nanocomposites [3]. We report how the cellulose nanofibrils

affect the structure of the liquid foam template and of the solid foam. The resulting nanocomposite

foams have improved mechanical properties, which, however, are not proportional to the amount of

cellulose nanofibrils. One reason for this observation is the disturbance of the cell structure of the

solid foams by the cellulose nanofibrils [4].

Figure 1. General scheme showing how the CNF content in the chitosan foam may alter the cell

morphology of the solid foams (bottom row of pictures), despite comparable liquid templates (top

row of pictures).

[1] S Andrieux, A Quell, C Stubenrauch and W Drenckhan, Adv Colloid Interface Sci. 256 (2018),

p. 276.

[2] S Andrieux, C Stubenrauch and W Drenckhan, Polymer 126 (2017), p. 425

[3] Y Wang et al. ChemNanoMat 3 (2016), p. 98.

[4] The authors acknowledge Dr. Alexander Fels for his support with the SEM measurements, and

Prof. Qi Zhou for assistance in the preparation of the CNF.

43

SL10 - Interaction of the Bio-Surfactant Aescin with biological model

membranes

Carina Dargel1, Ramsia Geisler1 and Thomas Hellweg1,2

1 Bielefeld University, Department of Chemistry, Universitätsstr. 25, 33615 Bielefeld, Germany 2 Bielefeld Institute for Nanosciene (BINAS), Bielefeld University, Universitätsstr. 25, 33615

Bielefeld, German

Saponins are plant derived surfactants which occur e.g. in nuts and garlic and exhibit an

amphiphilic structure built of a hydrophobic steroidic or triterpenic backbone with a varying

number of hydrophilic sugar chains. The interaction of saponins with biological membranes is not

yet scrutinized on a molecular level despite of the fact that they are used in pharmacy and

biochemistry to permeabilize lipid membranes. Some sapoins have very strong medical effects like

e.g. digitonin (main component of digitalis).

Therefore in this study the effect of the pure saponin escin [1] on small unilamellar vesicles of DMPC,

prepared by extrusion, is investigated mainly by different scattering methods in dependence on the

escin-amount and the temperature [2]. 1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC)

belongs is a phospholipids and vesicles made of it act as a model membrane in the present work.

Model membranes consisting of DMPC mimic biological membranes quite well and allow to study

effects of additives under different conditions, e.g. composition and temperature.

An incorporation of escin above a critical amount can be deduced from the investigated parame-

ters, namely the thermal phase transition temperature and vesicle size parameters like the radius,

membrane thickness and lipid head-to-head distance within one monolayer. Moreover, saponins can

interact with other pharmacologically relevant compounds [3].

Besides strutural and thermodynamic data also neutron spin-echo (NSE) results will be presented

[4]. NSE reveals the influence of escin on the bending elasticity of the DMPC model membranes

which depends on the phase state of the lipid.

References:

[1] C. Dargel, R. Geisler, Y. Hannappel, I. Kemker, N. Sewald, T. Hellweg, Colloids and Interfaces,

3 (2019) 47.

[2]R. Sreij, C. Dargel, L. Moleiro, F. Monroy, T. Hellweg, Langmuir, 33 (2017) 12351-12361.

[3] S. Sreij, S. Prévost, C. Dargel, R. Dattani, Y. Hertle, O. Wrede, T. Hellweg, Molecular

Pharmaceutics, 15 (2018) 4446-4461.

[4] S. Sreij, C. Dargel, P. Geisler, Y. Hertle, A. Radulescu, S. Pasini, J. Perez, L. H. Moleiro, T.

Hellweg, Physical Chemistry Chemical Physics, 2018, 20, 9070-9083.

44

SL11 - Formation of 2D Nanomembranes by Photopolymerization of

Diacetylene Lipids

Dominic Gilzer1, Roland Hillmann2, Lukas Goett-Zink1, Jessica L. Klocke1, Martina Viefhues2,

Dario Anselmetti2 and Tilman Kottke1

1 Physical and Biophysical Chemistry, Department of Chemistry / Bielefeld University, Bielefeld,

Germany 2 Experimental Biophysics and Applied Nanoscience, Department of Physics / Bielefeld University,

Bielefeld, Germany

2D Nanomembranes are promising materials for filtration or separation by providing the framework

for a controlled and rapid transport between two compartments. The polymerization of diacetylene-

containing lipids by illumination with UV light at the air/water interface produces freestanding 2D

nanomembranes with micrometer lateral dimensions [1]. We analyzed in situ the nanomembrane

formation of lipids with two (DiynePC) and one (PTPE) diacetylene-containing tails on germanium

using light-induced infrared difference spectroscopy with attenuated total reflection. The

assignment of the signals is supported by calculations using density functional theory. Upon

illumination, we observed the conversion of the diacetylene functional group in the monolayer.

Formation of the polymer network is evidenced by changes in frequency of C=O stretches acting as

infrared probes for the changes in the local environment. However, spectral and kinetic analysis

revealed a biphasic process in the monolayer. In the second phase, losses in signal of CH2 stretches

are observed which are not in agreement with the accepted mechanism for diacetylene

polymerization. An assignment to termination reactions is discussed. We suggest that limited 2D

mobility on the solid support promotes intramolecular termination leading to smaller domain sizes

of the polymer. In conclusion, IR spectroscopy provides an in-depth analysis of the formation of 2D

nanomembranes [2].

Figure 1. Light-induced IR difference spectra of the conversion of the lipid monolayer to a

nanomembrane (left). Proposed reaction mechanism deduced from the spectra (right).

[1] R Hillmann, M Viefhues, L Goett-Zink, D Gilzer, T Hellweg, A Gölzhauser, T Kottke and

D Anselmetti, Langmuir 34 (2018), 3256.

[2] TK acknowledges a Heisenberg Fellowship of the Deutsche Forschungsgemeinschaft

(KO3580/4-2).

45

SL12 - Directed Assembly of Multi-Walled Nanoribbons and Nanotubes of

Amino Acid Amphiphiles using a Layer-by-Layer Approach

Kathrin Voigtländer1, Luba Kolik-Shmuel2, Mingming Zhang2, Dganit Danino2, Marie-Sousai

Appavou3, Michael Gradzielski1

1 Stranski-Labor für Physikalische und Theroretische Chemie, Institut für Chemistry, Technische

Universität Berlin, Berlin, Germany 2 Department of Biotechnology and Food Engineering, Technion - Israel Institute of Technology,

Haifa 32000, Israel 3 Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), D-52425

Jülich/D-85748 Garching, Germany

Nanotubes with a very well-defined radius are formed by the amino acid amphiphile (AAA) K:C12-

β12 (N-α-lauryl-lysyl-aminolauryl-lysyl-amide). It self-assembles into stable nanotubes of great

length (several µm) and a diameter of ~100 nm by progressing from long thin fibers via twisted and

helically coiled ribbons to nanotubes [1].

In our experiments we show that such AAA nanotubes, where the surface charge is controlled by

pH, can be used as templates to produce multi-layered nanotubes. This was done by subsequent

deposition of oppositely charged polyelectrolytes on the nanotube followed by deposition of another

peptide shell in a layer-by-layer (LbL) approach (see Fig. 1). This deposition procedure can be

repeated and by subsequent LbL steps one can achieve the formation of multi-walled nanotubes

where the number of layers is controlled by the number of LbL steps. The structural changes taking

place during the formation process of these multi-walled AAA nanotubes were studied by

combining different techniques like scattering methods (SLS/DLS, SANS, SAXS), AFM and

direct-imaging methods (cryo- and dry TEM, SEM). This yielded a comprehensive understanding

of the structural details of the modified nanotubes with pH and surface charge as major control

parameters [2]. The obtained hybrid nanotubes are versatile nanostructured systems with future

application potential, e.g. in delivery systems and as smart materials.

Figure 1. Scheme of the layer-by-layer preparation process of multi-walled AAA nanotubes.

[1] L Ziserman, H-Y Lee, SR Raghavan, A Mor, D Danino, J Am Chem Soc 133 (2011), 2511.

[2] K Vogtländer, L Kolik-Shmuel, M Zhang, A Mor, M-S Appavou, C Jafta, D Danino. M

Gradzielski, submitted.

The authors acknowledge funding from the Deutsche Forschungsgemeinschaft, via DFG project

GR1030/14-1. DD acknowledges the support of the Israel Science Foundation grant No. 1117/16

and the Russell Berrie Nanotechnology Institute (RBNI).

46

SL13 - PNIPAM microgel-stabilized foams studied with neutron scattering

Matthias Kühnhammer, Oliver Löhmann and Regine von Klitzing.

Technical University Darmstadt, Department of Solid State Physics, Darmstadt, Germany

Cross-linked, short-chained poly-N-isopropylacrylamide (NIPAM) polymers have been in the focus

of numerous studies in the past years and are still being discussed very actively in the context of

multiple possible applications, because of their ability to respond to external stimuli like

temperature. A prominent example are thermo-responsive emulsions stabilized by microgel

particles adsorbed at the water-oil interface. In these systems the emulsion stability can be

controlled by changing the temperature [1,2].

In this study the interfacial activity of PNIPAM microgels is exploited to stabilize aqueous foams.

These foams are very stable at temperatures below the volume phase transition temperature (VPTT)

of NIPAM and can be destabilized by increasing the temperature above the VPTT.

Probing the internal structure of macroscopic liquid foams, like their film thickness, is very difficult

with optical methods, since foams strongly scatter light in the visible range. To overcome this

problem, small angle neutron scattering (SANS) can be used, as already demonstrated by Axelos et

al. [3].

In this contribution we will present results of SANS measurements with foams stabilized by

PNIPAM microgel particles. The thickness of the foam films and the structuring of the microgels

inside them will be analyzed for different foams stabilized by particles with varying cross-linker

density and size. This gives insights into the deformation of microgel particles inside the foam

lamellae. These findings, together with the properties of individual microgels (e.g. size, elasticity,

particle concentration), are used to explain the macroscopic foam properties, namely foamability

and foam stability [4].

[1] B. Brugger, B. Rosen and W. Richtering, Langmuir 24 (2008) p. 12202.

[2] V. Schmitt and V. Ravaine, Curr. Opin. Colloid Interface Sci. 18 (2013) p. 532.

[3] M. Axelos and F. Boué, Langmuir 19 (2003) p. 6598.

[4] The authors acknowledge funding from the Federal Ministry of Research and Education of

Germany (BMBF).

47

SL14 - Model-based Synthesis of Ferrocene Containing Microgels

Sabine Schneider1, Falco Jung2, Alexander Mitsos2 and Felix A. Plamper1,3

1 Institute of Physical Chemistry, RWTH Aachen University, Aachen, Germany 2 Aachener Verfahrenstechnik, Process System Engineering, RWTH Aachen University, Aachen,

Germany 3 Institute of Physical Chemistry, TU Bergakademie Freiberg, Freiberg, Germany

Microgels are well-known for their ability to adjust shape and volume in response to an external

trigger as for instance temperature, pH or an electrochemical stimulus [1]. To introduce multiple

stimuli into one system, different monomers can be incorporated into one microgel. Both monomer

composition and microgel architecture influence the resulting responsive properties. Therefore, it is

important to control the incorporation of a comonomer also with respect to its localization within

the microgel. E.g. it was found that vinylferrocene (VFc) is consumed faster than N-

isopropylacrylamide (NIPAM) in a batch precipitation polymerization of VFc and NIPAM, leading

eventually to core-shell microgels (VFc-rich core, NIPAM-rich shell) [2].

Here, we exploit a fed-batch synthesis to vary the specific localization of VFc in the microgel. To

circumvent time-consuming experimental trials, we use a mechanistic model to predict suitable fed

amounts and feeding times of VFc during the synthesis. Therefore, we estimate the

copolymerization parameters of the NIPAM-VFc system from kinetic data of the one-pot batch

synthesis yielding core-shell microgels. Using these parameters, we exploit the model to determine

synthesis procedures to tailor the VFc localization within the microgel (core, shell, homogeneous

distribution). No further adaption of these protocols was necessary to synthesize microgels with the

desired distribution of VFc in the microgel reproducibly [3].

Figure 1. Cryo-TEM images and sketches of the synthesized microgel architectures showing the

localization of vinylferrocene (in red color) in the core (left), the shell (middle) and homogeneously

distributed throughout the microgel (right)

[1] F. A. Plamper and W. Richtering, Accounts of Chemical Research 50 (2017), p.131.

[2] O. Mergel, S. Schneider, R. Tiwari, P. T. Kühn, D. Keskin, M. C. A. Stuart, S. Schöttner, M. de

Kanter, M. Noyong, T. Caumanns, J. Mayer, C. Janzen, U. Simon, M. Gallei, D. Wöll, P. van Rijn

and F. A. Plamper, Chemical Science 10 (2019), p.1844.

[3] The authors acknowledge funding from the German Research Foundation (DFG) within the

Collaborative Research Center SFB 985 Functional Microgels and Microgel Systems. We thank

Anne Nickel and Dr. Tobias Caumanns for the TEM measurements.

1000 nm 250 nm 250 nm

48

SL15 - Deswelling of microgels in crowded suspensions depends on crosslink

density and architecture

A. Scotti1, A. R. Denton2, M. Brugnoni1, J. E. Houston3, R. Schweins4, I. I. Potemkin5 and W.

Richtering1.

1 Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany 2 Department of Physics, North Dakota State University, Fargo, ND 58108-6050 USA) 3 European Spallation Source ERIC, Box 176, SE-221 00 Lund, Sweden. 4 Institut Laue-Langevin ILL DS/LSS, 71 Avenue des Martyrs, F-38000 Grenoble, France. 5 DWI - Leibniz Institute for Interactive Materials, Aachen 52056, Germany.

As shown in our most recent publication [1], microgels are nanometer-to-micron-sized crosslinked

polymer networks, that swell when dispersed in a solvent. These soft colloids have emerged as

versatile building blocks of smart materials, which are distinguished by their unique ability to adapt

their behavior to changes in external stimuli. Using X-ray and neutron scattering and molecular

simulation methods, we systematically measured and modeled the response to crowding of

compressible, deformable microgels with varying crosslink densities and internal architectures. Our

experiments and simulations demonstrate that incorporating a solvent-filled cavity during chemical

synthesis provides an independent means of controlling microgel swelling that complements the

influence of changing crosslink density. In other words, knowledge of the content of crosslinks

alone cannot be used to define microgel softness, but microgel architecture is another key property

that affects softness. These results are potentially important for biomedical applications, such as

drug delivery and biosensing.

Figure 1. Sketch of the possible responses to the increase of concentration of ultra-low crosslinked

(left), regularly crosslinked microgels (central) and hollow microgels (right).

[1] Scotti et al. Macromolecules: Accepted (2019)

49

SL16 - Particle size analysis of highly concentrated phase change dispersions by

Photon Density Wave spectroscopy

Daniela Vasquez1, Oliver Reich1 and Lena Bressel1

1 University of Potsdam, Institute of Chemistry/Physical Chemistry – innoFSPEC, Potsdam,

Germany.

Particle size analysis is a very important quality control in many different industries. As particle

size is linked to many physical properties (optical appearance, viscosity, etc.) it is a critical

parameter in manufacturing and in the performance of the final product. Additionally, monitoring

particle size distributions (PSD) and understanding how they affect the product, can give insights in

the success of many manufacturing processes. Due to the high concentrations of particles in

industrial products (> 60 %), common sizing techniques as Static (SLS) or Dynamic Light

Scattering (DLS) are not suitable. In contrast, PDW spectroscopy can be applied to highly turbid,

i.e. highly concentrated, materials to determine independently the optical properties like the

absorption coefficient a and the reduced scattering coefficient s’ without any dilution or

calibration. Using Mie theory and considering additionally models for particle interaction, particle

sizes can be determined from µs’ for mono- and bidisperse systems [1,2]. However, particle sizing

in polydisperse systems is still under investigation.

The aim of this study is to produce model dispersions with defined particle size distributions to be

analyzed by PDW spectroscopy. Highly concentrated phase change dispersions were prepared by

melt emulsification (20-50%) at high pressure in the presence of an emulsifier and subsequent

cooling to room temperature. The effect of wax and emulsifier concentration as well as temperature

on the particle size distributions was investigated in a comparative study of different particle size

techniques like SLS, DLS and PDW spectroscopy. Figure 1 shows exemplarily the growth of the

mean diameter for all studied techniques as the concentration of phase change material increases.

Further results will be presented [3].

0.2 0.3 0.4 0.5

200

300

400

500

Mea

n di

amet

er d

3 /

nm

Mass fraction WPCM

PDW DLS SLS

Figure 1. Volume weighted mean diameter, d3 as a function of phase change material concentration.

[1] L Bressel, R Hass, O Reich, Journal of Quantitative Spectroscopy and Radiative Transfer 126

(2013), p. 122.

[2] L Bressel, J Wolter, O Reich, Journal of Quantitative Spectroscopy and Radiative Transfer 162

(2015), p. 213.

[3] We acknowledge funding from BMBF program Unternehmen Region (Grant-No. 03Z22AB1B).

50

SL17 - Development of a Sample Environment for in-situ Dynamic Light

Scattering in Combination with Small Angle Neutron Scattering for the

Investigation of Soft Matter at the European Spallation Source

Andreas Josef Schmid1, Sebastian Jaksch2, Henrich Frielinghaus2, Tobias Schrader2, Georg Brandl2,

Harald Schneider3 and Thomas Hellweg1

1 Institute of Physical and Biophysical Chemistry, Bielefeld University, Bielefeld, Germany 2 Jülich Centre for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ,

Garching, Germany 3 Scientific Activities Division, FLUCO Platform, European Spallation Source ERIC, Lund,

Sweden

The most brilliant and most powerful neutron source in the world, the European Spallation Source

ESS, is currently built in Lund. In our project “FlexiProb” we develop three modular sample

environments for the investigation of soft matter samples to maximize the potential of the ESS with

regard to the very high neutron flux.

These are sample environments for small angle neutron scattering (SANS) with in-situ dynamic

light scattering (DLS), under gracing incidence (GISANS) and on free-standing liquid films and

foams. All sample environments are built on an universal carrier system to ensure a high

repeatability and flexibility as well as a minimum switching time between different sample

environments.

The in-situ DLS & SANS module developed in our subproject will provide additional control

parameters, in particular the sample stability, during the SANS measurements. We developed a

special sample holder for about 40 samples which allows the simultaneous measurement of SANS

and DLS at two different scattering angles and with a precise temperature control.

[1] The authors acknowledge funding from the German Federal Ministry of Education and Research

BMBF within the joint project “FlexiProb: Flexible Porobenumgebungen für die Untersuchungweicher Materie an der ESS”(05K2016).

Figure 1. Left: Design of the in-situ DLS/DWS module for DLS measurements at two fixed

scattering angles. Right: Current setup in the laboratory at Bielefeld University.

51

SL18 - Separation of multimodal colloidal mixtures using zonal rotor

centrifugation

Claudia Simone Plüisch1, Rouven Stuckert1, Brigitte Bössenecker2 and Alexander Wittemann1

1 Colloid Chemistry, Department of Chemistry, University of Konstanz, D-78457 Konstanz,

Germany. 2 Particle Analysis Center, Department of Chemistry, University of Konstanz, D-78457 Konstanz,

Germany

Originating in the 1950s, density gradient centrifugation using swinging-bucket rotors has become

an efficient tool in the isolation and purification of biological particles ranging from whole cells

down to serum proteins [1]. Owing to its high resolving power, a decade later, a program was

launched at the Oak Ridge National Laboratory that came up with hollow rotors capable of hosting

density gradients and therefore allowing separations at larger scales [2]. From then on, the

technique was solely used for biological separations. In its original field the technique is nowadays

widely superseded by chromatographic techniques and threatens to fall into oblivion. We will

demonstrate that waking this “sleeping beauty” opens up exciting perspectives apart from biology, namely in sorting mixtures of colloidal particles.

Clusters built from variable numbers of spherical particles are referred to as “colloidal molecules” because they share configurations with true molecules [3-5]. Mixtures of such supraparticles are an

ideal model system to probe fractionation of multimodal nanoparticles using zonal rotor

centrifugation (Fig. 1). With regard to “colloidal molecules”, zonal rotor ultracentrifugation can

contribute to overcome a major bottleneck in making them available at a scale sufficient to build

hierarchical organized superstructures [6].

Figure 1. A zonal rotor is a bowl-shaped hollow rotor that eliminates centrifuge tubes of any sort.

It can be regarded as a 360° extension of a swinging-bucket rotor. Sedimentation occurs within

sector-shaped compartments. Zonal rotors can be loaded and unloaded while spinning at a speed

sufficient to stabilize the density gradient.

[1] CA Price, “Centrifugation in Density Gradients”, (Academic Press, New York, 1982).

[2] NG Anderson, Natl. Cancer Inst. Monogr. 21 (1966), p. 9.

[3] CS Plüisch and A Wittemann, Macromol. Rapid Commun. 34 (2013), p. 1798.

[4] R Stuckert, CS Plüisch and A Wittemann, Langmuir 34 (2018), p. 13339.

[5] M Hoffmann, CS Wagner, A Wittemann, ACS Nano 3 (2009), 3326.

[6] The authors acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG) within

SFB 1214/A10.

52

SL19 - Exploring the colloid-to-polymer transition for ultra-low crosslinked

microgels from three to two dimensions

Steffen Bochenek1, Andrea Scotti1, Monia Brugnoni1 and Walter Richtering1

1 Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany

Microgels are solvent-swollen nano- and microparticles that show prevalent colloidal-like behavior despite their polymeric nature. In our recently published study[1] we investigate ultra-low crosslinked poly(N-isopropylacrylamide) microgels (ULC), which are synthesized without the addition of a crosslinker agent.[2] ULC microgels can behave like colloids or flexible polymers depending on dimensionality, compression or other external stimuli.

Small-angle neutron scattering shows that the structure of the ULC microgels in bulk aqueous solution is characterized by a density profile that decays smoothly from the center to a fuzzy surface. Their three-dimensional phase behavior and rheological properties are those of soft colloids.[3] However, when these microgels are confined at an oil-water interface, their two-dimensional phase behavior is significantly different from regularly crosslinked microgels[4] and resembles that of flexible polymers. Once monolayers of ultra-low crosslinked microgels are compressed, deposited on solid substrate and studied with atomic-force microscopy, a concentration-dependent topography is observed. Depending on the compression, the ULC microgels can behave as flexible polymers, covering the substrate with a uniform film, or as colloidal microgels leading to a monolayer of particles.

Figure 1. (Top): (a) Sketch of a ULC microgel in solution. (b) 3D phase behavior of ULC microgels. (Bottom): (c)-(f) AFM images of ULC microgel monolayers at the solid interface as a function of compression.

[1] A. Scotti, S. Bochenek, W. Richtering, et al., Nature Communications, 10 (2019) 1418.[2] J. Gao, B. J. Frisken, Langmuir, 19 (2003), 5212–5216.[3] H. Senff, W. Richtering, J. Chem. Phys., 111 (1999), 1705-1711.[4] M. Rey, L. Isa, et al., Soft Matter, 12 (2016), 3545-3557.[5] The authors acknowledge the Deutsche Forschungsgemeinschaft within the SFB 985“Functional Microgels and Microgel Systems” for financial support.

53

SL20 - Stimuli-Responsive Complex Emulsions as Novel Transducers in

Chemical and Biological Sensing Applications

Lukas Zeininger1,2, Timothy M. Swager2, and Markus Antonietti1

1 Department of Colloid Chemistry, Max-Planck Institute of Colloids and Interfaces, Potsdam,

Germany 2 Department of Chemistry and Institute of Soldier Nanotechnologies, Massachusetts Institute of

Technology, Cambridge, USA

Dynamic multiphase complex emulsions formed from two or more immiscible solvents offer a unique

platform for the generation of new triggerable materials. In designing our methods, we make use of

solvent combinations that are immiscible at room temperature but exhibit a lower (LCST) or upper

critical solution temperature (UCST). Emulsification of the mixture below LCST or above UCST

enables a simple one-step fabrication of complex multicomponent emulsions as well as structured

soft-matter particles with highly uniform morphology via temperature-induced phase separation. The

morphology of these dynamic liquid colloids is exclusively controlled by interfacial tensions and the

droplet geometries can be controllably altered after emulsification. Dynamic liquid colloids can

selectively invert morphology in response to external stimuli such as the presence of specific analytes,

small pH changes, light or high energy irradiation, and the presence of an electric or magnetic field

and thus provide a new active element for novel and existing applications of emulsions including

chemotaxis, the fabrication of optical metamaterials, and chemical/biological sensing. We explore

the potential of our dynamic micro-colloids to manipulate the pathway of light in response to

chemically triggered morphology changes. Dynamic morphological reconfiguration of microscale

refractive components in combination with the potential to incorporate a variety of active optical

media as well as stimuli-responsive elements enables the application of these purely liquid-based or

solidified micro-colloids as new transduction materials for chemo- and bio-sensing. Here, we will

demonstrate a series of optical transduction methods that are based on having control over the total

internal reflection of light from outside and inside multicomponent colloids. An associated

understanding of the unique chemical-morphological-optical coupling inside chemically

functionalized active soft matter colloids creates a solid foundation for the development of sensing

paradigms targeting a series of chemical and biological analytes, including a rapid and sensitive

method for the detection of common foodborne pathogens Escherichia Coli and Salmonella enterica

bacteria.

References:

[1] L. Zeininger et al., ACS Cent. Sci. 2019, DOI: 10.1021/acscentsci.9b00059.

[2] C. Lin, L. Zeininger, S. Savagatrup, T. M. Swager, J. Am. Chem. Soc. 2019, 141, 3802-3806.

[3] L. Zeininger, E. Weyandt, S. Savagatrup, K. S. Harvey, Q. Zhang, Y. Zhao, T. M. Swager, Lab

Chip 2019, 19, 1327-1331.

[4] Q. Zhang, L. Zeininger, K. Sung, E. Miller, K. Yoshinaga, H. D. Sikes, T. M. Swager, ACS

Sensors 2019, 4, 180-184.

54

SL21 - Structural properties of a pH and temperature responsive

telechelic pentablock terpolymer in dilute solution Florian Jung1, Panayiota A. Panteli2, Chia-Hsin Ko1, Jia-Jhen Kang1, Lester C. Barnsley3,

Constantinos Tsitsilianis4, Costas S. Patrickios2, Christine M. Papadakis1

1 Physics Department, Soft Matter Physics, Technical University of Munich, Garching, Germany 2 Department of Chemistry, University of Cyprus, Nicosia, Cyprus 3 Jülich Research Center GmbH, JCNS at MLZ, Garching, Germany 4 Department of Chemical Engineering, University of Patras, Patras, Greece

Stimuli-responsive physical hydrogels change their properties upon a small change of the

environment and may be used as fast sensors, for drug delivery or for tissue engineering. [1] Often,

these systems are based on physical hydrogels, where a stimuli-responsive midblock is end-capped

by hydrophobic blocks. In aqueous solution, the end blocks associate and act as physical crosslinks

which are bridged by the midblocks. The dynamics of the gel can be tuned by using temperature

responsive polymers as end blocks. It has been shown that these systems form a weak gel below the

lower critical solution temperature (LCST) of the end blocks, while a frozen network is formed

above. [2]

In this work, the structure of the telechelic pentablock terpolymer P(n-BuMA8-co-TEGMA8)-b-

PDMAEMA50-b-PEG46-b-PDMAEMA50-b-P(n-BuMA8-co-TEGMA8) in dilute aqueous solution is

investigated as a function of temperature and pH. The endblocks are statistical copolymers of the

thermoresponsive TEGMA (triethylene glycol methyl ether methacrylate) and the hydrophobic n-

BuMA (n-butyl methacrylate). The DMAEMA (2-(dimethylamino)ethyl methacrylate) block is a

weak cationic polyelectrolyte. PEG stands for poly(ethylene glycol) and is permanently hydrophilic.

Small-angle X-ray and neutron scattering reveals that the polymers form micelles with a spherical

core and a highly swollen corona (Fig. 1). Dynamic light scattering reveals the formation of finite

micelle clusters, but no hydrogel formation is observed. Decreasing the pH value leads to an

increase in micelle and cluster size, and the midblocks exist as dangling ends or bridges rather than

loops. The effect of temperature depends on the pH value: below the pKb of PDMAEMA, the

micellar size varies only weakly with temperature, whereas above, the micelle and cluster size

decrease with increasing temperature and the formation of loops is favored. In summary, the

polymer shows complex responsive solution behavior in dependence on temperature and the pH

value.

Figure 1. Schematic representation of the micelles in aqueous solution and their response to a

change in temperature or pH value.

[1] C. Tsitsilianis, Soft Matter 6 (2010), p. 2372

[2] C. Tsitsilianis, C.-H. Ko, F. Jung, C. M. Papadakis, C. S. Patrickios et al., Macromolecules 51

(2018), p. 2169

55

SL22 - Morphological Influences on the Shear Flow Behavior of Colloidal Rods

C. Lang1,2,J.K.G. Dhont1, C. Clasen M.P. Lettinga 1,2

1 ICS-3/Forschungszentrum Jülich, 52428, Jülich, Germany 2 Laboratory for Soft Matter and Biophysics, KU Leuven, 3000, Leuven, Belgium

p.lettinga@fz-juelich.de

High-aspect-ratio colloidal particles are becoming increasingly important in a wide range of

technological applications and products. In biology they constitute the frame of the cytoskeleton, in

the form of F-actin and micro tubular networks, while amyloids are responsible for e.g. Alzheimer

disease. The mechanical response of complex fluids containing rod-like colloids is hugely affected

by the particle morphology, though a direct relation has not been identified so far. The key to a bottom

up understanding is to identify the role of rod morphology on the microscopic structural response to

flow, underlying the macroscopic mechanical response.

Here, we use a library of monodisperse bio-engineering viruses with variable length and stiffness, for

which we determine the exact relation between structural and mechanical response by a combination

of rheology and Small Angle Neutron Scattering, resolving the orientational ordering of rod-like

viruses in the flow-gradient and the flow-vorticity plane [1].

This approach allowed us to determine the length dependence of the zero-shear viscosity, while we

extended existing theory to rationalize the shear thinning behavior. Furthermore, we identified the

effect of flexibility which diminishes viscosity at low shear rate and enhances it at high shear rates.

The elongational viscosity obeys theoretical predictions, while is diminishes with flexibility [2]. As

such, this work establishes a fundament for understanding the non-linear flow behavior of more

complex rod-like systems, which we demonstrate for ideal bi-disperse systems.

Figure 1. Zero-shear viscosity vs scaled columefraction as determined for a library of rod-like

viruses varying in length from 2.1 m (pf1) to 0.88 m (fd) and in stiffness (Y21M is 9 times

more stiff. Lines represent our theoretical prediction with a prefactor c for the rotational diffusion

due to Teraoka [3]. The inset displays c as a function of the relative flexibility Lp/L , where the

straight line represents the theoretical prediction by Teraoka et al. [2].

[1] C. Lang, J. Kohlbrecher, L. Porcar, M. P. Lettinga; Polymers 8 (2016); 291

[2] C. Lang, J. Hendricks, Z. Zhang, N. K. Reddy, J. P. Rothstein, M. P. Lettinga, J. Vermant and

C.Clasen. Soft Matter, 2019,15, 833.

[3] Teraoka I, Ookubo N, and Hayakawa R. Molecular theory on the

entanglement effect of rodlike polymers. Phys. Rev. Lett., 55:2712, 1985.

56

SL23 - Measuring Colloidal Dynamics in Turbid Suspensions

Denis Botin1, Jennifer Wenzl1, Holger Schweinfurth1, Daniel Crowley1, Riande Dekker1,2, and

Thomas Palberg1

1 Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz, Germany, 3 Physical and Colloid Chemistry, Utrecht University, 3584 CH Utrecht, The Netherlands

Charged colloidal particles in liquids with high dielectric constant form repulsion dominated fluid,

crystalline or glassy structures but also show electro-kinetic drift motion, when subjected to electric

fields. Key obstacle to their investigation at elevated concentration is multiple scattering (MS). We

here present a novel small angle Super-Heterodyne Dynamic Light Scattering (SH-DLS) scheme,

working at fixed low angle and accessing the intermediate scattering function directly in frequency

space without the need to employ Siegert’s relation. SH is realized employing a 2kHz frequency

shift between illumination beam and reference beam. Unwanted contributions of low frequency

noise, homodyne scattering and moderate MS are corrected for in a straightforward way and excel-

lent ensemble averaging is provided by a large detection volume. The instrument is introduced in

some detail and different applications demonstrated. Future perspectives of extension to q-depend-

ent measurements are discussed. In summary, our approach promises to become a very versatile too

for the investigation of colloidal dynamics in turbid and/or non-ergodic samples

Figure1: (from left to right, top to bottom) 1) small angle SH-Spectrum at 30% transmission; yel-

low: MS fit to be subtracted [1]. Cshet(q,) is directly proportional to the Fourier transform of

g(1)(q,t). After MS-correction, information on the solvent flow profile, the particle diffusion and its

drift velocity are obtained [2]. 2) electro-phoretic and -osmotic mobility as a function of particle

concentration [3] (Volume fractions from 10-4 to 5 10-2, fluid (F) or crystalline (C) order). 3) Grain

boundary self diffusion during crystallization and coarsening stages [1]. 4) Inward pumping current

of a spherical micro-fluidic osmotic pumps for differently charged substrates of differing electro-

osmotic mobilities [2]. 5) Double-arm goniometer based large-q SH-DLS. [3]. 6) Self-diffusion co-

efficients of a single scattering non-interacting sample from SH-DLS and from standard DLS [3].

[1] D. Botin et al. J. Chem. Phys. 146, 2017 204904. https://dx.doi.org/10.1063/1.4983688

[2] D. Botin et al. Soft Matter 14, 2018 8191-8204. https://doi.org/10.1039/C8SM00934A

[3] D. Botin, PhD-Thesis, Mainz 2019; D. Crowley, BA-Thesis, Mainz 2018

57

SL24 - Formation of Laves Phases in Repulsive and Attractive Binary

Mixtures of Buoyancy Matched Hard Spheres

N. Schaertl1, D. Botin2, M. Wernet1, S. Fischer1, T. Palberg2, E. Bartsch1

1 Institute of Physical Chemistry, Albert-Ludwigs-University, Freiburg, Germany 2Institute of Physics, Johannes Gutenberg University, Mainz, Germany

Laves phases (LPs) of MgCu2 type are considered to be promising precursors for diamond

structure photonic materials [1]. LPs are non-space-filling LS2 structures (with L denoting large

and S small spheres) showing different stacking sequences of two-layered hexagonal units of

L-spheres for the three types known in atomic systems: MgZn2, MgCu2 and MgNi2.

Experimental realizations of colloidal LPs have so far been reported for nanoparticles and

charged spheres. Realization of LPs with MgCu2 structure made of hard spheres (HS) would

greatly improve technical possibilities. We here studied the phase behavior and crystallization

kinetics in a binary mixture of Polystyrene microgel based HS approximants of size ratio

RS/RL=0.77 suspended under excellent buoyancy match in 2-Ethylnaphthalene. Systems of

number ratio NS/NL=3.2 were investigated at volume fractions in the fluid – LP coexistence

region. Analysis of the powder diffraction patterns shows at low concentration the formation of

LPs with MgZn2 structure and packing fraction = 0.590 in near quantitative agreement with

expectations from recent simulations [2]. With increasing , we observe the presence of a large

amount of small units with MgCu2-type stacking [3]. This is attributed to crystallization via

densified precursors from which the hexagonal units form and register randomly. Combinatoric

calculations then show that for random stacking half of the formed three-mers will show

MgCu2-type stacking. Thus, an increase of stacking faults results in the presence of a

thermodynamically unfavored structure. Introducing short-ranged depletion attraction by

adding non-adsorbing polymer chains, crystallization is quenched at low polymer concentration

while formation of only fcc crystals of S-spheres is observed at higher polymer concentrations.

Increasing the crosslink density from 1:50 (1 crosslink per 50 monomer units) to 1:10 (and,

thus, making repulsive interactions even more HS-like) crystallization is quenched altogether.

This indicates that the formation of the different crystal phases depends crucially on subtle

changes of particle interactions.

Fig. 1: LPs of MgZn2, MgCu2 and MgNi2 structure. Shown are the L-sphere positions. In atomic LPs the

stacking sequence is stabilized via the electronic structure of the components. In hard sphere colloid LPs

stacking faults may occur similar to the formation of r-hcp in single component HS colloids.

[1] A.-P. Hynninen, J. H. J. Thijssen, E. C. M. Vermolen, M. Dijkstra and A. van Blaaderen,

Nature Mater. 6 (2007), 202.

[2] A.-P. Hynninen, L. Filion and M. Dijkstra, J. Chem. Phys. 131 (2009), 64902.

[3] N. Schaertl,D. Botin, T. Palberg, E. Bartsch, Soft Matter 14 (2018), 5130.

58

SL25 - Formation of anisotropic gold nanoparticles in AOT-based template

phases

Joachim Koetz*, Ferenc Liebig

Institut für Chemie, Universität Potsdam, Potsdam, Germany

Nanoscale heating by optical excitation of plasmonic metal nanoparticles is of importance for

controlling chemical reactions. Especially, the temperature gradients around hot spots, i.e., at the tips

of anisotropic metal nanoparticles, are of relevance for SERS experiments. Therefore, different

strategies were developed for the synthesis of anisotropic metal nanoparticles. For example, ultrathin

gold nanotriangles can be synthesized in a mixed AOT/phospholipid based multivesicular template

phase [1]. The mechanism of the platelet formation can be described by an Ostwald ripening process

at the periphery of soft gold nanoparticle aggregates inside of the vesicles [2]. When the gold

reduction process is performed in AOT/CTAB based catanionic giant vesicles, only very small gold

clusters are formed. However, by adding ascorbic acid as a reducing agent in presence of silver nitrate

one can produce gold nanoflowers. In that case the platelets grow out of a gold core. The resulting

nanoflowers offer an excellent enhancement factor of 105 in SERS experiments [3]. In presence of

AOT micelles as a template phase nanostars with long spikes can be produced in a one-step procedure

(compare Figure 1). HRTEM micrographs show that the spike crystallization is preferred in <011>

direction, and EDX measurements verify a silver underpotential deposition on the spike surface. In

general, the results show that the template phase influence the growth of preliminary formed gold

clusters to larger aggregates, the cluster fusion (core formation), and the asymmetric growth of

platelets or spikes at the nanoparticle periphery.

Figure 1. TEM micrograph of a gold nanostar.

[1] F Liebig, RM Sarhan, C Prietzel, A Reinecke, J Koetz, RSC Advances 6 (2016) 33561.

[2] F Liebig, AF Thünemann, J Koetz, Langmuir 32 (2016) 10928.

[3] F. Liebig, R. Henning, R.M. Sarhan, C. Prietzel, M. Bargheer, J. Koetz, Nanotechnology 29

(2018) 185603.

[4] The authors acknowledge funding from the DFG, Grant Number KO 1387/14-1; INST 336/64-1

59

SL26 - Highly Dispersible Hexagonal Carbon-MoS2-Carbon Nanoplates with

Hollow Sandwich Structures for Supercapacitors

Ting Quan,1 Eneli Härk,1 Zdravko Kochovski,1 Shilin Mei,1 Matthias Ballauff,1,2 Yan Lu*1,3

1 Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie,

Hahn-Meitner-Platz 1, 14109 Berlin. 2 Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489 Berlin. 3 Institute of Chemistry, University of Potsdam, 14476 Potsdam.

In this work, a new sandwich structure made of hollow carbon-MoS2-carbon nanoplate was

successfully synthesized by an L-cysteine assisted hydrothermal method using gibbsite as a

template and polydopamine as a carbon precursor.[1] Gibbsite template used in this work featured

the hexagonal nanoplate structure and was synthesized through a large-scale colloidal method from

aluminum alkoxides.[2] After calcination and etching of the gibbsite template, uniform hollow

platelets, which are made of a sandwich-like assembly of the partial graphitic carbon and the two-

dimensional layered MoS2 flakes, were obtained. The platelets showed excellent dispersibility and

stability in water with good electrical conductivity due to the carbon coatings. The hollow

nanoplate morphology of the material provided a high specific surface area of 543 m2/g, a total

pore volume of 0.677 cm3/g and fairly small mesopores (~5.3 nm). The material was applied in a

symmetric supercapacitor and exhibited a high specific capacitance, suggesting that the hollow

carbon-MoS2-carbon nanoplates are promising candidate materials for supercapacitors.[3]

Figure 1. The highly dispersible hollow sandwich-structured carbon-MoS2-carbon nanoplates

have been successfully synthesized using hexagonal gibbsite nanoplates as template and

polydopamine as carbon precursor.

[1] L. Zhang, H. B. Wu, Y. Yan, X. Wang, X. W. Lou, Energy Environ. Sci. (2014), 7, 3302-

3306.

[2] J. Cao, C. J. Jafta, J. Gong, Q. D. Rang, X. Z. Lin, R. Felix, R. G. Wilks, M. Bar, J. Y. Yuan,

M. Ballauff, Y. Lu, ACS Appl. Mater. Interfaces (2016), 8, 29628-29636.

[3] T. Quan, N. Goubard-Bretesche, E. Hark, Z. Kochovski, S. L. Mei, N. Pinna, M. Ballauff, Y.

Lu, Chem.-Eur. J. (2019), 25, 4757-4766.

60

SL27 - Inline characterization of highly turbid dispersions during emulsion

polymerization using Photon Density Wave spectroscopy

Stephanie Schlappa1, Roland Hass1, Oliver Reich1, Lena Bressel1

1 University of Potsdam, Institute of Chemistry/Physical Chemistry - innoFSPEC, Potsdam,

Germany

Highly turbid liquids are of great importance in industrial applications and scientific research.

Complex liquids with high turbidity are processed in various industries like food, pulp and paper as

well as polymer, paint and coatings industry. With such high economic impact, it is important to

guarantee reliable inline analysis of these highly turbid liquids to ensure safety, process control and

reduction of waste. Most analytical methods commonly used in inline process analytics are

saturated already at low particle volume fractions and are not applicable for industrial applications

where volume fractions can easily exceed even 50 wt-%.

One method that has been proven to be reliable as a Process Analytical Technology is Photon

Density Wave (PDW) spectroscopy [1,2]. By independently determining the absorption coefficient

and the reduced scattering coefficient PDW spectroscopy can be used to access the chemical as well

as physical properties like particle size of a sample. Using intensity modulated laser light

transported via optical fibers process measurements can be achieved in samples with volume

fractions up to 50 wt-% using a probe. The probe has a small diameter, is robust against fouling and

allows for non-destructive analysis during the process either in a bypass or directly through a

reactor inlet. Inline PDW spectroscopy is hence a dilution- and calibration free method.

In this work, the inline characterization of a starved-feed emulsion polymerization process by PDW

spectroscopy is presented. As a model process the aqueous emulsion polymerization of vinyl acetate

with polyvinyl alcohol as protective colloid and a redox system as initiator is investigated. Volume

fractions up to 50 wt-% were successfully analyzed and dilution free measurements of particle size

and particle size distributions during the process by PDW spectroscopy showed good agreement to

offline dilution based reference methods like Dynamic Light Scattering (DLS) and Static Light

Scattering (SLS).

Tailoring of the emulsion polymerization was achieved by changing the amount of protective

colloid and changes in the feed rate of either monomer or protective colloid to reach particle size

distributions in the nanometer and lower micrometer scale with various degrees of polydispersity.

PDW analysis of the particle size distribution in the final product showed again good agreement to

conventional techniques like DLS, SLS and electron microscopy [3].

[1] L Bressel, R Hass, O Reich, Journal of Quantitative Spectroscopy and Radiative Transfer 126

(2013), p. 122.

[2] R Hass, O Reich, ChemPhysChem 12 (2011), p. 2572.

[3] We acknowledge funding from BMBF program Unternehmen Region (Grant-No. 03Z22AB1B

Grant-No. 03IH048A).

61

SL28 - All-in-one “schizophrenic” self-assembly of orthogonally tuned

thermoresponsive diblock copolymers

Natalya S. Vishnevetskaya1, Viet Hildebrand2, Noverra M. Nizardo2, Chia-Hsin Ko1, Peter Müller-

Buschbaum1,3, André Laschewsky2,4 and Christine M. Papadakis1

1 Physik-Department, Technische Universität München, Garching, Germany 2 Institut für Chemie, Universität Potsdam, Potsdam-Golm, Germany 3 Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany 4 Fraunhofer-Institut für Angewandte Polymerforschung, Potsdam-Golm, Germany

Smart, fully orthogonal switching was realized in a highly biocompatible diblock copolymer system

with variable trigger-induced aqueous self-assembly. The polymers are composed of nonionic and

zwitterionic blocks featuring lower and upper critical solution temperatures (LCSTs and UCSTs). In

the system investigated, diblock copolymers from poly(N-isopropyl methacrylamide) (PNIPMAM)

and a poly(sulfobetaine methacrylamide), systematic variation of the molar mass of the latter block

allowed for shifting the UCST of the latter above the LCST of the PNIPMAM block in a salt-free

condition. Thus, successive thermal switching results in “schizophrenic” micellization, in which the

roles of the hydrophobic core block and the hydrophilic shell block are interchanged depending on

the temperature (Figure 1, [1]). Furthermore, by virtue of the strong electrolyte-sensitivity of the

zwitterionic polysulfobetaine block, we succeeded to shift its UCST below the LCST of the

PNIPMAM block by adding small amounts of an electrolyte, thus inverting the pathway of

switching. This superimposed orthogonal switching by electrolyte addition enabled us to control the

switching scenarios between the two types of micelles (i) via an insoluble state, if the LCST-type

cloud point is below the UCST-type cloud point, which is the case at low salt concentrations or (ii)

via a molecularly dissolved state, if the LCST-type cloud point is above the UCST-type cloud point,

which is the case at high salt concentrations. Systematic variation of the block lengths allowed for

verifying the anticipated behavior and identifying the molecular architecture needed. The versatile

and tunable self-assembly offers manifold opportunities, for example, for smart emulsifiers or for

sophisticated carrier systems.

Figure 1. Fully orthogonal switching is realized by

inversion of block copolymer micelles via the

molecularly dissolved state or via large aggregates,

depending on salt concentration.

[1] NS Vishnevetskaya, V Hildebrand, A Laschewsky, P Müller-Buschbaum, CM Papadakis et al.,

Macromolecules 49 (2016), p. 6655, Macromolecules 50 (2017), p. 3985, Macromolecules 51

(2018), p. 2604. Langmuir, ASAP, DOI: 10.1021/acs.langmuir.9b00241.

[5] The authors acknowledge funding from Deutsche Forschungsgemeinschaft (DFG) and

Deutscher Akademischer Austauschdienst (DAAD). We thank A. Lieske, M. Walter, M. A.

Dyakonova, J.-J. Kang, K. Kyriakos, B.-J. Niebuur and K. Raftopoulos for their support.

62

SL29 - Supramolecular Colloids with Functionality and Switchability through

Light

Anja Krieger1, Anne Kutz1, Giacomo Marini1,2, Alexander Zika1, Ralf Schweins2, Franziska Gröhn1

1 Friedrich-Alexander-Universität Erlangen-Nürnberg, Department of Chemistry and Pharmacy and

Interdisciplinary Center for Molecular Materials (ICMM), Erlangen, Germany; 2 DS/LSS Institut Laue-Langevin, Grenoble, France.

With regard to the world's decreasing energy resources, developing strategies to exploit solar energy become more and more important. Inspired by natural systems it is highly promising to self-assemble building blocks into functional supramolecular units. In this talk we will present a new type of photocatalytically active nano-objects in aqueous solution consisting of macroions and oppositely charged species ranging from ionic porphyrins to inorganic nanoclusters. Through the self-assembly, the photocatalytic activity of the active species can be enhanced up to a factor of 20, and a novel selectivity can be achieved. 1-3

Electrostatic self-assembly leads to nanoscale shapes ranging from spheres and cylinders over vesicles to networks. Key to a targeted structure design is to fundamentally understand structure directing effects. In this contribution we reveal how the molecular building block structure directs the supramolecular nanoscale structure, in particular the colloid particle size and shape on a 10-100 nm level. Thermodynamics and the interplay of interaction forces will be discussed.4-6

In addition, we describe light-triggered size and shape changes of electrostatically self-assembled supramolecular nanostructures, following different strategies.7-9 This route for the conversion of light into mechanical energy is highly promising for applications in drug delivery, nanosensors and solar energy conversion.

Self-assembled colloids are characterized by SANS, static and dynamic light scattering, AFM, -potential measurements and spectroscopy. A general relationship of molecular structure, enthalpy/entropy balance and assembly size and shape will be presented.

1 A. Kutz, G. Mariani, R. Schweins, C. Streb, F. Gröhn, Nanoscale, 2018, 10, 914.

2 A. Krieger, J.-P. Fuenzalida Werner, G. Mariani, F. Gröhn, Macromolecules 2017, 50, 3464.

3 A. Kutz, W. Alex, F. Gröhn, Macromol. Rapid Commun. 2017, 38, 1600802.

4 G. Mariani, R. Schweins, F. Gröhn, Macromolecules 2016, 49, 8661.

5 G. Mariani, A. Kutz, Z. Di, R. Schweins, F. Gröhn, Chemistry – A European Journal 2017, 23, 6249.

6 G. Mariani, D. Moldenhauer, R. Schweins, F. Gröhn, J. Am. Chem. Soc. 2016, 1378, 1280.

7 I. Willerich, F. Gröhn, Angew. Chemie Int. Ed. 2010, 49, 8104.

8 C. Cardenas-Daw, Carlos, F. Gröhn, J. Am. Chem. Soc. 2015, 137, 8660.

9 D. Moldenhauer, F. Gröhn, Chemistry – A European Journal 2017, 23, 3966.

63

SL30 - Supracolloidal Atomium

Jacopo Cautela1, Björn Stenqvist2, Luciano Galantini1 and Jérôme J. Crassous2,3

1 Department of Chemistry, Sapienza University of Rome, Rome, Italy 2 Physical Chemistry, Department of Chemistry, Lund University, Lund, Sweden 3 Institute of Physical Chemistry, RWTH Aachen University, Aachen, Germany

While colloids have been widely employed as models for atoms and molecules, the current study

proposes to extend their use as building blocks for supracolloidal frameworks. Hereby, the self‐assembly between highly anisotropic supramolecular microtubules and soft spherical fluorescent

microgels is explored using confocal laser scanning microscopy. The influence of the particle size

and charge with respect to the tubule composition, which consists either of bile salt derivatives or

naphtoilamine substituted cholate, is investigated. Under certain conditions, microgel particles are

found to specifically interact with the extremities of the tubular aggregates and hierarchically self‐assemble into various superstructures varying from virus‐ like assemblies to supracolloidal networks.

The reported approach is envisioned to open new self‐ assembly routes toward ordered hybrid

superstructures where the spherical colloids act as responsive linkers of tubular structures [1].

Figure 1. a) Supracolloidal network between microgels and supramolecular naphta-derivative tubules

(fluorescent + transmission). b) 3D reconstruction of the network. c) Atomium building in Brussels.

[1] J Cautela, V Lattanzi, LK Månsson, L. Galantini and JJ Crassous, Small 4 (2018) 4, p. 1803215

64

SL31 - Formation of silver nanoparticles in monoolein-based lyotropic liquid

crystals in the absence and presence of DNA

Dmitry Kushnikovskiy1, Azat Bilalov2 and Claudia Schmidt1

1 Paderborn University, Department of Chemistry, Paderborn, Germany 2 Kazan National Research Technological University, Physical and Colloid Chemistry Department,

Kazan, Russia

Nanostructured metallic materials have received much attention due to their unique optical, electric

and magnetic properties, compared to the corresponding bulk materials [1]. Many methods of

nanoparticle preparation have been explored, which are often based on a templating approach. This

contribution reports on the formation of silver nanoparticles in lyotropic liquid crystals and on how

it is affected by the presence of DNA. The formation of silver nanoparticles from AgNO3 in both

the binary system monoolein (MO)/water and in the ternary system docecyltrimethylammonium-

DNA/MO/water [2] will be compared. UV/vis spectroscopy is used to detect the characteristic

plasmon resonances of the nanoparticles. Particle shapes and their size distribution are investigated

by electron microscopy. A spontaneous formation of silver nanoparticles was found in MO/water

since the lipid acts as reducing agent [3]. Over a period of two weeks, two peaks evolve in the

UV/vis spectra (Figure 1, left), which can be assigned to nanoparticles of different shapes. When

the lyotropic mesophase contains DNA, the spontaneous formation of nanoparticles is slowed down

significantly (Figure 1, right). This can be explained by a complexation of Ag+ by the DNA base

pairs [4], which makes them less accessible. If the DNA-containing phase is exposed to UV

radiation, however, nanoparticle formation occurs on the time-scale of several tens of minutes.

300 400 500 600 700 8000.0

0.2

1.2

1.4

Abs

orba

nce

(a.u

.)

Wavelength (nm)

9 weeks 8 weeks 7 weeks 6 weeks 5 weeks 4 weeks 3 weeks 2 weeks 1 week 5 min

Figure 1. Temporal evolution of UV-Vis spectra of nanoparticles formed spontaneously in the

cubic Ia3d phase of monoolein-based systems in the absence (left) and presence (right) of DNA.

[1] C Burda, XB Chen, R Narayanan and MA El-Sayed, Chem. Rev. 105 (2005), p. 1025.

[2] A Bilalov, J Elsing, E Haas, C Schmidt and U Olsson, J. Colloid Interf. Sci. 394 (2013), p. 360.

[3] S Puvvada, S Baral, M Chow, SE Qadri and ER Ratna, J. Am. Chem. Soc. 116 (1994), p. 2135.

[4] L Berti, A Alessandrini and P Facci, J. Am. Chem. Soc. 127 (2005), p. 11217.

[5] The authors acknowledge funding from the DFG Research Training Group GRK 1464 and from

DAAD.

65

SL32 - Strong ferronematic coupling with anisotropic LC polymer brush

particles

Karin Koch1, Matthias Kundt1, Alex Eremin2 and Annette M. Schmidt1

1 Department Chemie, Institut für Physikalische Chemie, Universität zu Köln, Köln, Germany 2 Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, Magdeburg,

Germany

Controlling the director in thermotropic liquid crystals (LC) by means of external fields is a powerful

tool in a wide range of applications, e.g. in optical devices. Usually such devices are operated by

electric voltage, while an analogous employment of magnetic fields is principally an option, yet

drawn back by the need for high magnetic flux densitity due to the low magnetic anisotropy of the

mesogenic molecules.

In order to increase the effect of magnetic fields on liquid crystal phases, it has been proposed

to use fine magnetic particles as dopants [1] and has ever since inspired a number of experimental

approaches to ward such magnetically doped liquid crystal phases. However, it turned out that one of

the main challenges for the experimental realization is the strong tendency of the nanoparticles to

agglomerate, as a consequence of the strong molecular interactions of the mesogens and the dipolar

interactions between the particles. Thus, compatibilization is a key step for the development of

ferronematics. Our novel approach towards ferromagnetically doped LCs with enhanced volume

fraction and stability of the magnetic dopants is based on a general approach to surface-modify

magnetic nanoparticles with a side-chain LC polymer brush (fig. 1a). We employ two different

synthetic pathways with a variation of shell thickness, mesogen density and spacer length. This results

in an effective steric stabilization of the particles against agglomeration and offers a high degree of

surface density with respect to the mesogen.

We carefully investigate the phase behaviour of 5CB when doped with different, appropriately

surface-modified magnetic nanoparticles, divergent in size, shape and magnetic anisotropy and under

variation of the particle volume fraction. Our results from differential scanning calorimetry (DSC),

refractometry and polarized optical microscopy consistently indicate a significant improvement in the

compatibility and stability as compared to conventionally stabilized particles. The magnetic response

of the ferronematic phases is investigated by capacitance measurements in a magnetic field. As

compared to 5CB, the critical field strength is shifted to significantly lower magnetic field strengths

(fig.1b). The data is fitted based on available theories, indicating a strong coupling between the

magnetic and the nematic director in these systems.

Figure 1. a) Scheme of LC polymer brush particle, b) Capacitance measurements in parallel B and

E field for pure 5CB (black), and for 5CB doped with 9OCB-PHMS@CoFe2O4 with a volume

fraction between 0.01 vol% and 0.1 vol%.

References

[1] F. Brochard, P. P. G. de Gennes, J. Phys., 31, 691–708, 1970.

66

SL33 - Lyotropic liquid crystals as templates for mesoporous silica materials

Johanna R. Bruckner1, Jessica Bauhof1, Jacqueline Gebhardt1, Ann-Katrin Beurer2, Yvonne Traa2

and Frank Giesselmann1

1 Institute of Physical Chemistry, University of Stuttgart, Stuttgart, Germany. 2 Institute of Chemical Technology, University of Stuttgart, Germany.

Hexagonal lyotropic liquid crystals (LLCs) are formed by a regular array of rod shaped micelles

with their long axes being aligned along a common direction. Thus, they are ideal templates for the

synthesis of mesoporous materials. An added silica precursor which solely dissolves in the continu-

ous aqueous phase, polycondensates around the micelles during hydrothermal treatment. After re-

moving the template, an inverse of the former hexagonal LLC phase is obtained. Such mesoporous

silica materials (pore size: 2–50 nm) can be used for a variety of applications, e.g. energy storage,

synthesis of nano-particles, adsorption or drug delivery. Furthermore, they play a key role in the

lately granted CRC 1333 [1]. Crucial for its success is a precise control of the pore size and shape.

Even though there are some publications about lyotropic liquid crystal templating [2], only little is

known about the templating process itself as well as the correlation between the LLCs and the

mesoporous material’s structure. Therefore, we systematically investigate various synthesis

methods and production parameters while analyzing intermediate and final products as well as

the corresponding LLC phases by a wide range of methods such as SAXS, N2-adsorption and TEM

(see Figure 1). Our study provides new insights into the role of the LLC phases in the templating

process and improve the tailored design of new mesoporous materials.

Figure 1. Structural changes during the templating process measured by small angle X-ray

diffraction (left). TEM image of the final mesoporous silica material (right).

[1] https://www.crc1333.de/

[2] G. S. Attard, J. C. Glyde, C. G. Göltner, Nature 378, 366-368 (1995); P. Feng, X. Bu, D. J. Pine,

Langmuir 16, 5304-5310 (2000); S. G. Wainwright, C. M. A. Parlett, R. A. Blackley, W. Zhou, A.

F. Lee, K. Wilson, D. W. Bruce, Microporous and Mesoporous Materials 172, 112-117 (2013).

[3] Financial support by the DFG (CRC1333) is gratefully acknowledged.

67

SL34 - Directing the Orientational Alignment of Anisometric Magnetic

Nanoparticles using Dynamic Magnetic Fields

D. Zákutná1,2, P. Bender3, D. Honecker2, S. Disch1

1 Department für Chemie, Universität zu Köln, Köln, Germany 2 Institut Laue-Langevin, Grenoble, France 3 University of Luxembourg, Luxembourg

The response of magnetic nanoparticles to applied static and dynamic magnetic fields is the subject

of intense research in view of its fundamental technological importance, e.g. for medical applications

such as imaging and magnetic hyperthermia [1], or sensor applications [2]. The field-assisted self-

assembly of shape-anisotropic nanoparticles in dispersions is particularly desired for liquid crystalline

or optically anisotropic materials [3] and as a prerequisite for self-organization into long range

ordered arrangements with anisotropic physical properties [4].

Whereas magnetic nanorods commonly align with their long axis parallel to an applied magnetic

field, weakly ferromagnetic hematite nanospindles bear a magnetic easy axis in their crystallographic

basal plane and are thus known to orient with their principal axis perpendicular to an applied magnetic

field [5,6]. We have recently determined the field-dependent magnetic and nematic order of the

magnetic single-domain nanospindles in static magnetic field [7]. Whereas Small-Angle X-ray

Scattering (SAXS) gives information on the morphological particle orientation, Wide-Angle X-ray

Scattering (WAXS) texture analysis elucidates the atomic scale orientation of the magnetic easy

direction in the crystal structure. Our results strongly suggest the tendency for uniaxial anisotropy but

indicate significant thermal fluctuations of the particle moments within the hematite basal plane.

In addition to the particle orientation distribution obtained by static SAXS, we will highlight the

dynamic reorientation behavior of hematite nanospindles in alternating and rotating magnetic fields

using time-resolved SAXS. For frequencies between the characteristic rotational frequencies of the

principal and equatorial axes, parallel alignment of the elongated magnetic nanoparticles with their

principal axis perpendicular to the rotation plane is expected. The found dynamic reorientation

behavior is further exploited towards self-organization. Using a dynamic field-induced self-assembly

process, we developed nanoparticle arrangements with parallel and perpendicular orientation towards

the substrate that exhibit directionally anisotropic magnetic properties [8,9].

[1] Q. A. Pankhurst, J. Connolly, S. K. Johnson, J. Dobson, J. Phys. D: Appl. Phys. 36 (2003) R167.

[2] D.T.N. Chen et al., Ann. Rev. Cond. Mat. Phys. 1 (2010) 301.

[3] G. M. Whitesides, B. Grzybowski, Science 295 (2002) 2418.

[4] A. Ahniyaz, Y. Sakamoto, L. Bergström, Proc. Natl. Acad. Sci. U.S.A. 104 (2007) 17570.

[5] A. Satoh et al., J. Colloid Int. Sci. 292 (2005) 581.

[6] L. Roeder, P. Bender et al., J. Polym. Sci. Pol. Phys. 50, 1772 (2012).

[7] D. Zákutná, Y. Falke, D. Dresen, S. Prévost, P. Bender, D. Honecker, S. Disch, Nanoscale 11,

7149 (2019).

[8] D. Hoffelner, M. Kundt, A. M. Schmidt, E. Kentzinger, P. Bender, S. Disch, Faraday

Discussions 181 (2015) 449.

[9] We acknowledge the ESRF, Grenoble, France, for providing the synchrotron radiation facilities

at beamlines ID02 and ID13 and JCNS for provision of access to the GALAXI instrument.

Dr. S. Prévost, Dr. M. Burghammer, Dr. M. Sztucki, and Dr. E. Kentzinger are acknowledged for

their support in data acquisition. Financial support from the German Research Foundation (DFG:

Emmy Noether Grant DI 1788/2-1) is gratefully acknowledged.

68

SL35 - Ordered Particle Arrays via a Langmuir Transfer Process: Large Area

Access to Any Two-Dimensional Bravais Lattice

Miriam E.J. Mauer1, Christian Stelling1, Bernd A.F. Kopera1, Fabian A. Nutz1, Matthias Karg3,

Markus Retsch1,2, Stephan Förster4,5

1 Physical Chemistry 1, University of Bayreuth, Bayreuth, Germany 2 Bavarian Polymer Institute, University of Bayreuth, Bayreuth, Germany3 Physical Chemistry I, Heinrich-Heine-University, Düsseldorf, Germany 4 JCNS-1/ICS-1, Forschungszentrum Jülich, 52425 Jülich, Germany 5 Physical Chemistry, RWTH University, 52074 Aachen, Germany

The preparation of particle arrays on solid substrates is an essential step for the fabrication of

functional surfaces and thin-film devices with applications in lithography, optics, photonics, high-

density data storage and as adhesive/non-adhesive surfaces. Colloidal self-assembly represents an

attractive and scalable route towards hexagonally close-packed particle arrays. Up to now, however,

it is hardly possible to realize two-dimensional symmetries other than hexagonal packing. To

significantly broaden the structural variability, the fabrication of non-close-packed and also non-

hexagonal particle arrays is required. Here, we demonstrate how to fabricate non-close-packed

particle arrays with symmetries of all possible Bravais lattices in a simple solution-based process

[1]. Our process starts with readily self-assembled, hexagonally close-packed monolayers, which

are immobilized on an air/water interface. Upon transfer onto the target substrate, stretching along a

specific crystallographic direction occurs. This yields non-close-packed structures with non-

hexagonal symmetry (Figure 1). We demonstrate how to control the stretching factor by interfacial

modification of the target substrate to access all possible Bravais lattices. Our process tremendously

opens the possibilities provided by colloidal lithography, since it offers a versatile approach for

batch or continuous fabrication of non-close packed particle arrays with per-determined

symmetry.[2]

Figure 1. Particle monolayers are stretched to yield the five possible Bravais lattices in the two-

dimensional space. (From left to right) Square, hexagonal, centered rectangular, rectangular, and

oblique. Scale bars are 1 μm.

[1] Hummel et al., Langmuir 2019 35 (4), 973

[2] This work was funded by the German Research Foundation (DFG) by the SFB840. M.E.J.H.,

C.S., and B.A.F.K. acknowledge support from the Elite Network of Bavaria (ENB).

69

SL36 - Shape-directed programmable assembly of colloidal machines

Yunus Alapan1, Berk Yigit1, Onur Beker1, Ahmet Demirors2 and Metin Sitti1,

1 Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart,

Germany 2 Department of Materials, ETH Zurich, Zurich, Switzerland

Micromachines comprising diverse parts can carry out sensing, manipulation and other tasks, or be

integrated into more complex systems, enabling life-inspired hierarchical assemblies. To this end,

field-directed and self-propelled colloidal assembly have been used to build mobile and

reconfigurable colloidal walkers, swimmers and spinners [1-3]. However, integrating heterogeneous

components into a micromachine with specified structure, function and dynamics remains a

significant challenge. We introduce a directed assembly process via pre-programmed physical

interactions between structural and motor sub-units for building mobile micromachines with desired

configurations. The assembly is driven by dielectrophoretic interactions, encoded in three-

dimensional shape of the individual parts. Micromachines assembled from magnetic and self-

propelled motor parts exhibit reconfigurable locomotion modes and additional rotational degrees of

freedom not available to conventional monolithic microrobots. The versatility of this site-selective

assembly strategy is demonstrated on different reconfigurable, hierarchical, and 3D micromachine

assemblies. Our results demonstrate how shape-encoded assembly pathways enable programmable,

reconfigurable mobile micromachines, without relying on multi-material composites and intricate

surface chemistry modifications. We anticipate the presented design principle will advance and

inspire the development of more sophisticated, modular micromachines, and their integration to

multiscale hierarchical complex systems [3].

Figure 1. Shape-encoded assembly of motor sub-units to a 3D microprinted body. (a, b) A 3D

microcar body design for generation of site-selective attractive DEP forces. Color bar: (E/E0)2. (c)

Directed assembly of the magnetic motor units and (d) translation of the assembled microcar under

a rotating magnetic fields. All scale bars are 25 µm.

[1] B. Yigit, Y. Alapan and M. Sitti, Advanced Science 6 (2019), 1801837.

[2] A. Aubret, M. Youssef, S. Saccana and J. Palacci, Nature Physics 14 (2018), p. 1114.

[3] S. Ni, E. Marini, I. Buttinoni, H. Wolf and L. Isa, Soft Matter 23 (2017), p. 4252.

[4] Dr. Y. Alapan thanks Alexander von Humboldt Foundation for the Humboldt Postdoctoral

Research Fellowship. Dr. A. Demirors acknowledges the Swiss National Science Foundation for the

Scientific Exchange grant, IZSEZ0_181526. This work is funded by the Max Planck Society.

70

Posters

71

72

AM1 - Study of Sedimentation Behavior of Mono- and Oligo-Disperse Suspensions with the MultiScan Setup

Hanih Paydar1,2 Martin Grüßer2, Michaela Laupheimer2, Christian Schöttle2, Thomas Sottmann1

1 University of Stuttgart, Institute of Physical Chemistry, Stuttgart, Germany 2 DataPhysics Instruments GmbH, Raiffeisenstraße 34, 70794 Filderstadt, Germany

The sedimentation process is a very important field in both, fundamental research and industrial

application. Sedimentation is influenced by a variety of parameters: the counteracting buoyancy,

friction and gravity forces [1], but also hydrodynamic forces and interaction between the particles

[2].For many years the standard technique to study sedimentation was to carry out shelf-life tests, a

quite subjective and therefore unreliable method. Contrary the MuliScan technique is allows to

analyze sedimentation processes and its rates for disperse colloidal systems. By measuring the

intensities of transmitted and backscattered light, reproducible sedimentation data can be obtained in

a short time.In this project we studied the influence of several parameters, such as particle size,

temperature, concentration on the sedimentation rate. Additionally, uniformity (mono- or

oligodisperse suspensions) was varied as a parameter to study the interaction in these dispersions [3].

Theoretical models (e.g. from Stokes’ Law [4]) were used to describe the experimental data.

Figure 1. Microscope of

monodisperse spherical polystyrene

particles with a diameter of 15.3

µm.

Figure 2. Sedimentation process of 15.3 µm polystyrene

particles in aqueous solution at 30 °C: photos (top left);

sedimentation analysis in the MultiScan software (right); and

calculated sedimentation rate with help of the MultiScan

software (bottom left).

[1] H.C. Troy and P.E. Sharp, Dairy Sci, II (1928) 189.

[2] Kourki, H. and Famili, M. H. N., “Particle sedimentation: effect of polymer concentration onparticle–particle interaction,” Powder Technology (2012) 137–143. [3] Coulson and

Richardson's, Chemical Engineering: Elsevier (2019) 420.

[4] Robinson, C. D., “Some Factors Influencing Sedimentation,” Ind. Eng. Chem., vol. 18, no. 8,

pp. 869–871, 1926.

73

AM2 - Synthesis and characterization of nanoporous polymers and hybrid

materials for heterogeneous catalytic applications

Karina Abitaev1, Yaseen Qawasmi1, Petia Atanasova2, Joachim Bill2 and Thomas Sottmann1.

1 Institute of Physical Chemistry, University of Stuttgart, Stuttgart, Germany. 2 Institute for Material Science, University of Stuttgart, Stuttgart, Germany.

Polymer nanofoams are a promising class of tailor-made substrates to study the role of confinement

in molecular heterogeneous catalysis, which is the main goal of the Collaborative Research Center

1333 "Molecular Heterogeneous Catalysis in Confined geometries". Within this project we use the

Nanofoams by Continuity Inversion of Dispersion (NF-CID) principle [1] to synthesize polymer

nanofoams. The fundamental idea behind NF-CID is the utilization of colloidal crystals of

thermoplastic polymer nanoparticles as a template.

In the study at hand, the influence of the size and polydispersity (PDI) of the nanoparticles along with

the NF-CID process parameters (temperature, pressure and exposure time) on the obtained porous

polymers were investigated. Polystyrene (PS) and poly(methyl methacrylate) (PMMA) nanoparticles

were synthesized via emulsion polymerization, followed by gently drying of the dispersion, leading

to the formation of a close-packed colloidal crystal. By varying the surfactant concentration, the

nanoparticle size, PDI and packing order of the obtained colloidal crystals are adjustable. While the

crystals of monodisperse particles PDI < 0.10 show a high packing order, the crystals of the

polydisperse particles PDI > 0.10 are denser packed. Interestingly, foaming experiments showed, that

the latter led to porous polymers with smaller pores. In addition, the pore size and morphology of the

porous polymer were found to depend highly on the temperature, exposure time and the expansion

step. Reaching the onset of continuity inversion, the coarsening of pores is promoted when

temperature and exposure time is increased. A modification of the expansion process by means of

controlled pressure release led to a homogeneous open-cellular foam with pores slightly larger than

the size of the used nanoparticles. Furthermore, a porous PS/ZnO hybrid material was obtained via

chemical bath deposition of the porous polystyrene, while retaining the general porous structure [2].

Figure 1. (left) SEM-image of the closed packed colloidal crystal-like of PS nanoparticles. (middle)

SEM images of porous PS obtained from the colloidal crystal via NF-CID process, using scCO2 at p

= 250 bar, T = 65 °C, and an exposure time of 15 min. (right) porous PS /ZnO hybrid material (right)

after 10 deposition cycles.[2]

[1] R. Strey, A. Müller (2010), DE Pat. 102 010 053 064 A1

[2] Y. Qawasmi, P. Atanasova, T. Jahnke, Z. Burghard, A. Müller, L. Grassberger, R. Strey, J. Bill,

T. Sottmann, Colloid and Polymer Science. 296 (2018), 1805-1816

Financial support from the German research foundation under grant no. CRC1333 is gratefully

acknowledged.

74

AM3 - Magnetic Nanoparticle/Polymer Brush Composite Materials: Adsorption

Behaviour and Structure

Philipp Ritzert1, Dikran Boyaciyan1, Larissa Braun1, Olaf Soltwedel1, Luca Silvi2, Regine v.

Klitzing1.

1 TU Darmstadt, Alarich-Weiss-Str. 10, 64287, Darmstadt, Germany 2 Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109, Berlin

Polymer chains, which are end-grafted chemically to a substrate, are referred to as polymer brushes,

showing a stretched chain conformation at sufficiently high grafting densities. Additionally, they

exhibit responsive behaviour depending on the specific monomer, classifying them as ‘smart materials’ [1]. One prominent example are thermo-responsive Poly(N-isopropylacrylamide)

(PNIPAM) brushes that are swollen in water at room temperature but collapse above a lower critical

solution temperature (LCST) and expel the incubated water. Besides, polymer brushes are a suitable

matrix for the immobilisation of nanoparticles enabling the manufacture of composite materials

with novel properties, e.g. the development of optical brush-based sensors [2].

Previous results demonstrated the successful attachment of pH-sensitive citrate-capped magnetic

CoFe2O4 nanoparticles (MNPs) to PNIPAM brushes. The adsorption behaviour was controlled by

pH value and MNP concentration of the incubation suspension. The advantage of this approach is

the ability to separately control and investigate the properties of the MNPs and the PNIPAM brush

prior to attachment. The pH value controls the (de-)protonation of the citrate capping, resulting in a

change of the MNP surface charge as well as the potential for hydrogen bond formation between the

PNIPAM brush and the MNPs. Figure 1 shows AFM micrographs of a neat PNIPAM brush and two

composite materials with different MNP loading, demonstrating control of the MNP attachment. On

the other hand, an increase in the MNP concentration of the incubation suspension leads to a higher

MNP adsorption.

In the present study, the internal structure of the composite materials is investigated by neutron

reflectometry in water, utilising contrast variation of the scattering length density (SLD) of the

swelling water. The reflectivity data are analysed by a self-written fitting procedure based on

volume fraction profiles of all chemical components [3].

Figure 1: AFM micrographs of different composite materials: a neat PNIPAM brush (left), and

PNIPAM brushes after incubation in MNP suspensions of pH 7 and different MNP concentration

(0.1 wt% middle, 0.2 wt% right).

[1] Christau, S. et al. Zeitschrift für Physikalische Chemie (2015) 229(7-8) 1089-1117

[2] Boyaciyan, D. et al. Soft Matter (2018) 14(20) 4029-4039

[3] Schneck, E. et al. Langmuir (2013) 29(46) 14178-14187

75

AM4 - Iron Oxide Nanoparticles Encapsulated into Hollow Carbon

Nanospindles as Sulfur Host for Lithium Sulfur Batteries

Dongjiu Xie1,2, Shilin Mei1, Zdravko Kochovski1, and Yan Lu1,2*

1 Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin for Materialian und Energie,

Hahn-Meitner-Platz 1, 14169 Berlin, Germany 2 Institute of Chemistry, University of Potsdam, 14467 Potsdam, Germany

Recently, a lot of efforts are devoted into lithium sulfur battery system due to its high theoretical

capacity (1675 mAh g-1) and low cost, which could be a competitive candidate for energy storage in

the future. However, it suffers from a poor cycling stability during charging-discharging, which is

blamed to the notorious “shuttle effects” of lithium polysulfides (Li2Sx, 4≤ x≤8) [1-2]. In our study,

functional metal oxide nanoparticles prepared by a colloidal route have been used as cathode host

materials for lithium sulfur batteries. Firstly, β-FeOOH nanospindles with a length of 250-300 nm

and a diameter of 60 nm were successfully synthesized through the hydrolysis of FeCl3 in

cetyltrimethylammonium bromide (CATB) solution in large batch [3]. After coating with

polydopamine and followed with annealing at high temperature, iron oxide was designed to be

encapsulated into hollow cabon nanospindle with a york-shell structure to suppress the “shuttle effect”. An improved performance has been obtained via the combination of physical adsorption of

the hollow carbon nanospindle and chemical adsorption of iron oxide, respectively. Moreover, it is

revealed that the york-shell structure plays an important role in the improvement of electrochemical

performance.

Figure 1. SEM and TEM images of the synthesized β-FeOOH nanospindles (a, b) and

polydopamine coated ones (c).

[1] Quan Pang, Xiao Liang, Chun Yuen Kwok and Linda F. Nazar, Nature Energy, 1.9(2016),16132

[2] M. Wild, L. O’Neil, T. Zhang, R. Purkayastha, G. Minton, M. Marinescu and G. J. Offer,

Energy & Environmental Science, 8(2015), 3477-3494

[3] Xiong Wang, Xiangying Chen, Lisheng Gao, Huagui Zheng, Mingrong Ji, Chenming Tang, Tao

Shen and Zude Zhang, Journal of Materials Chemistry 14 (2004), 905-907.

76

AM5 - Impact of Nanoparticles' Surface Properties on their Physico-Chemical

Behavior in Pickering Emulsions Sebastian Stock1, Annika Schlander2, Dmitrij Stehl1, Ariane Weber3, Sandra Forg1, Reinhard

Schomäcker3, Markus Gallei2, Regine von Klitzing1

1Department of Condensed Matter Physics, TU Darmstadt, Alarich-Weiss-Straße 10, 64287

Darmstadt, Germany 2Ernst Berl-Institute for Technical and Macromolecular Chemistry, TU Darmstadt, Alarich-Weiss-

Straße 4, 64287 Darmstadt, Germany 3Institute for Chemistry, TU Berlin, Straße des 17. Juni 124, 10623 Berlin, Germany

Pickering Emulsions (PEs) are emulsions stabilized by particles that adsorb at the oil water interface

and prevent coalescence of the droplets[1]. The aim of the current work is to use PEs as a reaction

environment for catalytically activated reactions for example for the hydroformylation of 1-

dodecene [2]. The expensive and water-soluble Rh-catalyst is retained in the water phase while the

oil phase can be separated via filtration using the high stability of

PEs [3]. It was found that a positively charged particle surface increases the particle-catalyst-

interaction. This leads to an increase in the reaction conversion [4]. The aim of the present study is

to explain this effect and to investigate the processes occurring at the interface in general. As a first

approach, differently modified particles including silica and polystyrene nanospheres are used to

stabilize PEs. The intended differences in surface charge, hydrophobicity and their natural

differences in size and material as well as the interaction with the Rh-catalyst are quantified by

Transmission Electron Microscopy (TEM), Atomic Force Microscopy, Dynamic Light Scattering

and Sessile Drop Contact Angle Measurements and the influence on their surface-active behavior in

PEs is studied by Fluorescence (FM) and Optical Microscopy. The measurements show that

modified silica spheres represent a suitable reference system for the investigation of the influence of

distinguished particle properties on macroscopic PE properties

Figure 1. A TEM Image of the modified silica nanospheres (SNS), B Fluorescence microscopy image

of (SNS) stabilized PE (water phase dyed with fluorescein), C Decrease of ζ-potential of positive

Polystyrene Spheres with increasing catalyst concentration shows catalyst particle interaction

References [1] S. U. Pickering: CXCVI.—Emulsions, J. Chem. Soc., Trans. 91 1907, p. 2001–2021

[2] R. von Klitzing, D. Stehl et al., Halloysites Stabilized Emulsions for Hydroformylation of Long

Chain Olefins, Adv. Mater. Interfaces 4 (1) 2017, 1600435

[3] D. Stehl, L. Hohl, M. Kraume et al., Characteristics of Stable Pickering Emulsions under Process

Conditions, Chemie Ingenieur Technik 88 (11) 2016, p. 1806–1814

[4] D. Stehl., N. Milojević, S. Stock, Schomäcker, R. von Klitzing, Synergistic Effects of a Rhodium Catalyst on Particle-Stabilized Pickering Emulsions for the Hydroformylation of a Long-Chain Olefin

Ind. Eng. Chem. Res. 58 (7) 2018, p. 2524–2536

77

AM6 - Flocculation and delayed sedimentation induced by osmotic effect in

polymer free aqueous suspensions

T. Sobisch1, and D. Lerche1,2 1 LUM GmbH, Berlin / Germany 2 Dr. Lerche KG, Berlin / Germany

Delayed sedimentation, e.g. collapse of transient gels [1] is an interesting phenomenon. Despite its

relevance for storage of complex formulations this topic is only sparsely researched. “In a transient

gel the particles aggregate, by the depletion interaction, to form a space-spanning network which

maintains its structural integrity for a finite period before suddenly collapsing” [1]. Depletion

interactions are mostly associated with the presence of non-adsorbing polymers. However, weak

flocculation and delayed sedimentation should be also induced by weakening the solvation layer

around particles by hygroscopic monomeric solutes.

This assumption was examined by investigating settling of polydisperse titan dioxide suspensions at

gravity varying solid content and mixing ratio water-glycerol. Separation kinetics were measured

using STEP-Technology (space and time resolved extinction profiles) with LUMiReader PSA und

LUMiReader X-Ray instruments (LUM, Germany). The latter allows to measure concentration

profiles directly, including the sediment region.

Indeed, as expected, delayed sedimentation occurs at sufficiently large glycerol concentrations (50

% m/m and higher). However, increasing electrostatic repulsion flocculation can be suppressed.

This suggests that in the case under investigation weak flocculation is governed by a sensitive

balance between repulsive particle interactions and osmotic destabilization.

[2]

[1] L Starrs, WCK Poon, DJ Hibberd and MM Robins, Collapse of transient gels in colloid–polymer mixtures, J. Phys.: Condens. Matter 14 (2002) p. 2485–2505.

[2] The authors acknowledge funding by AiF, Next STEP (ZF 4627 101AJ8).

78

AM7 - Effect of plasma modification on metal oxide nanoparticles - core shell

structures for better and similar dispersibility – evaluation by Hansen

dispersibility parameter

T. Sobisch1, L. Rodriguez2, D. Lerche1,2, C. Vandenabeele3, A. Usoltseva3 and S. Lucas3

1 LUM GmbH, Berlin / Germany 2 Dr. Lerche KG, Berlin /Germany 3 University of Namur, Namur Institute of Structured Matter, Namur / Belgium

Dispersibility of agglomerated/aggregated nanoparticles is of key interest for application in various

suspension based formulations. To make an economic use of raw materials a high degree of

dispersion of agglomerates has to be obtained. This is related also to practical aspects like achieving

high hiding power at lower pigment concentration and of outstanding material properties in

composites. Dispersibility in a given matrix obviously depends on chemical nature of the primary

nanoparticles. Surface modification allows to tune dispersibility characteristics specifically. It was

presumed that after plasma coating by polymer layer similar physicochemical compatibility and

dispersibility in a given matrix can be achieved independently of the starting material [1].

To test this hypothesis low-pressure plasma polymerization of cyclopropylamine was employed for

the surface functionalization of commercial metal oxides composed of primary nanoparticles

(University of Namur). Powder samples were characterized by XPS, FTIR and TEM.

Hansen dispersibility parameter were determined by quantifying particle sedimentation of

suspensions in various solvents by analytical centrifugation (LUMiSizer). Effect of dispersing

intensity (bath via tip sonication) was evaluated. This proofed that, as expected towards low

dispersing intensity, importance of specific interactions with solvents in the deagglomeration step

increases. In case of low intensity sonication, indeed plasma modified particles exhibited nearly

identical Hansen dispersibility parameter. Noticeably, at high sonication intensity the respective H-

bonding contributions did not only deviate in between the plasma modified metal oxides but also

exhibited a marked drop of values. In conclusion, for higher intensity of dispersing solvent ability

for hydrogen bond formation gets less important. This was interpreted in terms of cohesivity of

agglomerates is partly provided by hydrogen bonds and/or intra particle bonds which may be

broken by hydrogen bond formation.

[1] S. Mathioudaki, B. Barthélémy, S. Detriche, C. Vandenabeele, J. Delhalle, Z. Mekhalif and S.

Lucas, ACS Appl. Nano Mater. 1 (2018), p. 3464-3473.

79

AM8 - Biodegradable Polymer Foams via Foamed Emulsions M. Dabrowski1, S. Varytimiadou1, C. Stubenrauch1

1 University of Stuttgart, Institute of Physical Chemistry, Stuttgart, Germany

Porous biopolymers synthesized via the polymerization of high internal phase emulsions (HIPEs)

are becoming increasingly interesting as scaffolds in tissue engineering. In this case, the scaffold

must consist of a biopolymer with a three- dimensional architecture whose pores are interconnected

and are preferably monodisperse [1].

In the case of hydrophobic monomers, a promising alternative to emulsion templating is the

polymerization of foamed oil-in-water emulsions. With this templating route, one can synthesize

polydisperse and monodisperse porous polymers whose pore walls are also porous, which may be

advantageous for the transport of nutrients through the scaffold. However, unlike HIPEs, the use of

foamed emulsion as templates for porous polymers is still in its infancy. To the best of our

knowledge, there are only three studies in which this route was used, all three dealing with styrene

as monomer [2, 3, 4]. Note that a surfactant-stabilized monomer-in-water emulsion must be

formulated in the first place, which is then foamed because hydrophobic monomers cannot be

foamed. After having foamed the monomer-in-water emulsion the challenge is to retain the template

structure during the polymerization.

Our aim is to synthesize low-density polymer foams via microfluidics which are either

monodisperse or whose polydispersity is controllable. The polymer foams are synthesized via

foaming and polymerizing 1,4-butanediol dimethacrylate-in-water emulsions (Figure 1). By varying

the gas pressure, we are able to generate templates with different bubble sizes and thus polymer

foams with different pore sizes.

Figure 1. Synthesis of a monodisperse polymer foam via a foamed monomer-in-water emulsion

with microfluidics.

[1] C Colosi et al., Langmuir 29 (2013), 82.

[2] F Schüler et al., Angew. Chem. Int. Ed. 51 (2012), 2213.

[3] A Quell et al., Adv. Eng. Mat. 17 (2015), 604.

[4] J. Elsing et al., Phys. Chem. Chem. Phys. 19 (2017), 5477.

500 µm 500 µm 100 µm

80

AM9 - Mussel-inspired stimuli-responsive PNIPAM-microgels

Sandra Forg1 and Regine von Klitzing1 1 Dep. of Physics, Soft Matter at Interfaces, TU Darmstadt, Germany Polymer hydrogels offer unique properties. Especially their responsiveness to external stimuli including pH, ionic concentration and temperature provides a huge potential for various technological applications. The present work aims combining this stimuli-responsiveness with adhesive attributes. This novel hybrid might have a high impact for applications within biomedical fields (tissue engineering or medical purposes). Recently, hydrogels inspired by marine organisms such as mussels have become highly attractive. Mussels can strongly adhere to other substrates even under harsh conditions, which is mainly determined by the protein 3,4-dihydroxyphenyl-L-alanine (DOPA). In Fig. 1 the adhesion process of the catechol-group of DOPA is illustrated. The DOPA group can be incorporated into the hydrogel structure. However, most of these hydrogels are mechanically soft and / or possess a low elastic modulus, which remarkably limits their use in in vivo environments.

Figure 1. Adhesion of DOPA through hydrogen bonding (reduced state) and through metal chelation (oxidized state) The goal of this work is the synthesis of mechanically strong hydrogels with high adhesive potential, mechanical robustness and a good biocompatibility. For this purpose, poly(N-isopropylacrylamide) (PNIPAM) microgels are synthesized via precipitation polymerisation. PNIPAM microgels have a volume phase transition temperature (VPTT) of around 32°C, which can be shifted to higher temperature by copolymerisation of charged monomers or to lower temperature by addition of salt or amphiphiles. They are modified with DOPA to obtain adhesive properties. The DOPA content can be tuned from 15-30% according to the mussel byssus structure. Their charge is varied by copolymerisation with the anionic monomer acrylic acid (AA). Moreover, their size and cross-linker content can be tuned, which controls their mechanical and rheological properties.

The properties of these hydrogels are studied by DLS and Zetasizer measurements in order to determine the VPTT via changes of size and of surface charge. Afterwards, thin films of these DOPA-modified microgels are produced by spin-coating. They are analysed by static and dynamic indentation measurements. These measurements offer the possibility to get an insight into the mechanical and rheological properties on a nanoscopic scale of thin films.

81

AM10 - Colloidal Micro- and Nanopropellers for Actuation through Biological

Media

Tian Qiu1,2, Florian Ralf Peter2, Mariana Alarcón-Correa1, Vincent Mauricio Kadiri1,2, Zhiguang

Wu1, Debora Walker1,2, Cornelia Miksch1, and Peer Fischer1,2

1 Micro, Nano and Molecular Systems Lab, Max Planck Institute for Intelligent Systems, Stuttgart,

Germany 2 Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart,

Germany

Colloids that are to be actuated in biological systems first need to overcome the complexity of these

viscoelastic media. They thus require specific shapes and material properties that cannot easily be

achieved with traditional wet synthesis methods, instead requiring the implementation of other

fabrication methods, such as physical vapor deposition.

We have reported the use of glancing angle deposition (GLAD) for the fabrication of shape and

material tunable colloids, which can be actuated using chemical agents or magnetic fields [1,2]. The

ability to combine different materials during fabrication allows facile chemical surface modification

of colloids with magnetic properties. The actuation of nanopropellers by a rotating magnetic field, is

not only achieved in water based systems (Newtonian fluids), but also in hyaluronan gel, as a model

for non-Newtonian systems [2].

Furthermore, functionalization or passivation of the surface of magnetic micro propellers allows

them to overcome the restriction in respect to the mesh size of the media, while allowing for larger

surface areas for cargo transport real biological dense tissue –the vitreous humour of the eye. We

thus present that a swarm of colloidal particles actively propel through the vitreous and land on the

retina, actuated by an external magnetic field [4,5,6].

Figure 1. Various nano- and microstructures made by GLAD: a) TiO2 screws with Ni segment on

SiO2 nano seeds, b) SiO2 rods, c) TiO2-Si-Co zig-zag structure, d) Ag0.5 Cu0.5 alloy nano helices

[3], e) First time demonstration of magnetically-actuated microstructure propulsion through dense

biological media (vitreous humour) [5].

[1] T.-C. Lee, et al., Nano Lett., 14, 5, (2014), 2407-2412.

[2] Schamel, D. et al., ACS Nano, 8, (2014), 8794-8801.

[3] J.G. Gibbs, et al., Nanoscale, 6, (2014), 9457–9466.

[4] D. Walker, et al., Science Advances, 1, 11, (2015), e1500501.

[5] Z. Wu, et al., Science Advances, 4, 11, (2018), eaat4388.

[6] The authors acknowledge S. Jagiella for the help with FTIR, and J. Hurst, M. Stang, F.

Ziemssen, S. Schnichels for many useful discussions and contributions to the ophthalmology work.

82

AM11 - Swimming Direction of Active Colloids as a Function of pH

Nikhilesh Murty 1, Dhruv Singh 1 and Peer Fischer 1,2 1 Max-Planck-Institut für Intelligente Systeme, Heisenbergstraße 3, 70569, Stuttgart, Germany. 2 Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany. Microorganisms use chemical reactions to actively move at low Reynolds number in a fluid. Synthetic colloids have been designed to achieve the same albeit with a different propulsion mechanism [1]. One such class of particles with a spherical geometry are Janus particles, where the hemispheres have different properties leading to an anisotropy across the particle. Since the nature of the propulsion of these particles can be significantly affected by a change in their environment, understanding this dependency becomes essential. Colloidal particles partially coated with TiO2 and dispersed in a solution of hydrogen peroxide have been known to display directional motion under the illumination from a UV-light source [2]. Typically, the colloids swim towards their inert-face owing to self-diffusiophoresis [3]. However, upon increasing the pH of the medium, the particles move with the catalyst facing forward [4]. The swimming speed decreases upto a limiting value as the alkalinity of the medium is increased. Clustering of the particles is also observed at higher pH. The observations from this study can be used to further our understanding of the phoretic mechanisms that are responsible for the motion of these particles [5]. These effects can be employed to control the motion of these particles. [1] Gomez-Solano, J. R. et al., Sci. Rep. 7 (2017), 14891. [2] Singh, D. P., Choudhury, U., Fischer, P. and Mark, A. G., Adv. Mater. 29 (2017), 1701328. [3] Howse, J. R. et al., Phys. Rev. Lett. 99 (2007), 048102. [4] Brown, A. and Poon, W., Soft Matter 10 (2014), p. 4016. [5] Yu, T. et. al., Chem.Commun. 54 (2018), 11933.

83

SA1 - Sodium dodecylsulfate hydrolysis: Influence on the structure and rheological behavior of SDS-pDADMAC polyelectrolyte surfactant complexes (PESC)

Olga Kuzminskaya1, Ingo Hoffmann2, Daniel Clemens3, Michael Gradzielski1 1 Stranski-Laboratorium, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, 10623 Berlin, Germany 2 Institut Max von Laue-Paul Langevin (ILL), Grenoble Cedex 9, 38042 France 3 Helmholtz-Zentrum Berlin, 14109 Berlin, Germany

Since their early discovery, surfactants have found wide range of applications starting with personal care products [1] and ending with drug delivery systems [2]. Upon mixing an ionic surfactant and an oppositely charged polyelectrolyte (PE) formation of complexes (PESC) is induced. Moreover, some of these complexes show pronounced changes in viscosity. One of such systems comprising cationically modified hydroxyethyl cellulose and sodium dodecylsulfate (SDS) was investigated before in thorough detail [3]. SANS measurements revealed formation of the mixed rod-like aggregates, which interconnect several PE chains thereby enhancing the viscosity (see Fig.1).

Figure 1. PESC of cationically modified cellulose and SDS: Interconnected via rod-like aggregates PE chains with PE penetrating the surfactant core of the aggregate [3].

In the current study, PESC of SDS and poly(diallyldimethylammonium chloride) pDADMAC were investigated with the emphasis on the surfactant purity. In order to mimic the SDS hydrolysis, dodecanol, the hydrolysis product, was added to the SDS solution in different concentrations. Rheological measurements of prepared PECS showed a pronounced increase in a specimen viscosity when dodecanol was incorporated into the system and the viscosity increased as the concentration of the contaminant raised. Small angle neutron scattering (SANS) in the bulk contrast showed presence of disk-like aggregates, while PE contrast revealed rod-like structures of pDADMAC. Introduced dodecanol contamination also showed a visible influence on the structure in PE contrast, as the pronounced peak of a form factor got more smeared with the contaminant concentration. Hence, hydrolysis adduct of SDS surfactant showed noticeable effect on both the viscosity and the structure of the formed PESC.

[1] L. Rhein et al., Surfactants in Personal Care Products and Decorative Cosmetics, 3rd Edition, CRC Press, (2006). [2] J. Morales et al., Therapeutic delivery. 2, 623-41, (2011). [3] I. Hoffmann, M. Gradzielski, et al., Chem. Phys. 143, 074902 (2015).

84

SA2 - Syntheses and Characterization of Hydrophobically Modified

Polyacrylate Containing Block Copolymers

Özge Azeri1, Dennis Schönfeld1, Anja F. Hörmann1, Laurence Noirez2, Michael Gradzielski1

1 Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie,

Technische Universität Berlin, D-10623 Berlin, Germany 2 Laboratoire Léon Brillouin (CEA-CNRS), Uni. Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette,

France

Amphiphilic block copolymers have attracted great attention due to their unique properties and

numerous potential applications. [1,2] Their self-assembly property enables their applications in

many different areas including medicine, biology, biomaterials, microelectronics, photoelectric

materials, catalysts, etc. One of the most commonly studied systems are linear two or more block

amphiphilic copolymers. In this study, diblock copolymers containing hydrophobic and hydrophilic

group were designed and synthesized via one of the most efficient technique, Atom Transfer

Radical Polymerization (ATRP). The hydrophobic modification was varied with butyl, hexyl and

dodecyl acrylate groups and alkyl chain block length was 20 or 40. After syntheses of the designed

polymers, their aggregation behaviour in aqueous solution was characterized to investigate the

effect of hydrophobicity and pH dependence of the polymers. Critical micelle concentration (cmc)

of the polymers was determined via fluorescence spectroscopy (FS). Small-angle neutron scattering

(SANS) (Fig.1) and dynamic and static light scattering (DLS-SLS) experiments were done to

investigate the structures and size of these self-assembly systems with different degrees of

deprotonation.

Figure 1. SANS curve to show the effect of the different hydrophobic moieties (alkyl chains) and

the block length in the block copolymers for 0.5 wt% concentration and full ionisation

[1] E. Lejeune et al., Amphiphilic Diblock Copolymers with a Moderately Hydrophobic Block:

Toward Dynamic Micelles, Macromolecules, 43, 2667-2671 (2010

[2] S. Riemer et al., Aggregation behaviour of hydrophobically modified polyacrylate – Variation of

alkyl chain length, Polymer, 70, 194-206 (2015)

[3] The authors are grateful to the Laboratoire Léon Brillouin for allocation of SANS beam time,

and to Research group of Prof. Schlaad from University of Potsdam for performing the GPC

measurements.

85

SA3 - From Regular Solutions to Structured Microemulsions: Critical

Fluctuations versus Amphiphilic Film Formation

Shih-Yu Tseng1, Ulf Olsson2, Reinhard Strey3, Yun Liu4, and Thomas Sottmann1

1 Institute of Physical Chemistry, University of Stuttgart, Stuttgart, Germany 2 Division of Physical Chemistry, Lund University, Lund, Sweden 3 Institute of Physical Chemistry, University of Cologne, Cologne, Germany 4 Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, USA

The amphiphilic film, which stabilizes and separates the water- and oil-rich domains, plays the key-

role in the formation of structured microemulsions. Previous studies addressed the pathway from

regular ternary mixtures to microemulsions [1]. Small angle neutron scattering (SANS) experiments

performed in bulk-contrast proved the gradual build-up of water and oil domains along this route.

However, a detailed study of the emergence of a well-defined surfactant film is lacking. Thus, the

aim of this study is to use film-contrast SANS to prove the gradual formation of a surfactant film by

increasing the amphiphilicity of the surfactant. Moreover, the proof that systems “before” the tri-critical point (Figure 1, top left) has no surfactant film will refute recent publications on surfactant-

free microemulsions, which claim the accumulation of only weak amphiphile at the interface [2].

Starting with the system H2O – cyclohexane – 2-propanol/1-propanol, the critical point is adjusted

at equal volume of water and oil ensuring the tie-lines of the miscibility gap being parallel to the

water-oil side of the Gibbs phase diagram. Thus, critical fluctuations occur mostly in the direction

of the tie-lines allowing for matching of the bulk-contrast to detect the amphiphile in the interface.

Preliminary SANS results show that, the scattering data from the bulk-contrast can be described by

Ornstein-Zernike (OZ), which indicates the presence of critical fluctuations near the critical point

(Figure 2). Furthermore, the scattering intensity I(q) decreases with increasing distance from the

critical point (increasing . With respect to film-contrast we found out, that the deuteration of

components strongly affects the position of the critical point and thus the slope of the tie-lines.

Thus, SANS measurements of perfectly matched bulk-contrast are planned after the critical point

has been readjusted to equal volume of water and oil. A disappearing scattering intensity would

then provide the proof that surfactant-free microemulsions are rather dominated by critical

fluctuations and thus should be considered as regular solutions.

[1] M. Kahlweit, R. Strey and G. Busse, Phy. Rev. E 47 (1993), p. 4197–4209.

[2] T. N. Zemb et al., Proc. Natl. Acad. Sci. 113 (2016), p. 4260–4265.

Figure 1. Scheme of this study: phase

diagrams, scattering contrasts and spectra.

Figure 2. SANS curves of bulk contrast D2O –

cyclohexane – 2-propanol-OD/1-propanol-OD

with = 0.50 and = 0.25 at T = 25.0°C.

A B

C*

2

I

q

Matching of Bulk Contrast

a = b

subdomain

a

subdomain

b

r

surfactant film

subdomain

a

subdomain

b

r

x

2A B

C

3

x

D2O - cyclohexane - 2-propanol-OD/1-propanol-OD

~ 0.50, = 0.25

q / Å-1

0.001 0.01 0.1 1

I ( q

) /

cm

-1

1

10

100 = 0.5224

= 0.5280

= 0.5404

= 0.5523

= 0.5960

= 0.6793

IOZ

(q)

86

SA4 - Influence of Chemical Structure and Architecture on Self-Assembly

of Thermo-responsive Amphiphilic Block Copolymers

Michelle Hechenbichler1, Michael Gradzielski2, Cristiane Henschel1, André Laschewsky1,3,

Benjamin von Lospichl2 and Albert Prause2 1 Department of Chemistry, Universität Potsdam, Potsdam-Golm, Germany 2 Department of Chemistry, Technische Universität Berlin, Berlin, Germany 3 Fraunhofer Institute for Applied Polymer Research IAP, Potsdam-Golm, Germany.

The self-assembly of amphiphilic polymers has led to manifold applications particularly in the field

of cosmetics and detergents [1]. When introducing thermo-responsive blocks, the aggregation

behavior of these polymers can be controlled by changing the temperature (Figure 1). Within this

context, thermo-responsive associative telechelics have arisen particular interest. While confined to

simple diblock copolymer systems for long, the complexity - and thus the versatility - of such smart

systems can be strongly enlarged, once designed monomers, specific block sizes, different

architectures, or additional functional groups such as hydrophobic stickers are implemented [2-5].

We are exploring the structure-property relationships of responsive amphiphilic block copolymers by

varying their structure systematically. These block copolymers are synthesized by consecutive

reversible addition fragmentation chain transfer (RAFT) polymerizations. Focusing on

poly(acrylamide)s, we base our systems on poly(N,N-dimethylacrylamide) as permanently

hydrophilic block, and attach long alkyl chains as permanently hydrophobic end groups ("stickers").

We modify this basic molecular design by thermo-sensitive blocks made from different acrylamides

showing lower critical solution temperature (LCST) behavior. The aggregation in water is

investigated via turbidimetry and scattering methods. The results demonstrate how the various

molecular parameters influence the LCST transition and the aggregation behavior.

Figure 1. Self-assembly of a linear block copolymer in aqueous solution with a hydrophobic

end group (red), a hydrophilic block (blue) and a thermoresponsive block (green).

[1] A. Laschewsky, C. Herfurth, A. Miasnikova, F. Stahlhut, J. Weiss, C. Wieland, E. Wischerhoff,

M. Gradzielski, P. Malo de Molina, ACS Symp. Ser. 1148 (2013), p. 12.

[2] F. Laflèche, T. Nicolai, D. Durand, Y. Gnanou and D. Taton, Macromolecules 36 (2003), 36,

p.1341.

[3] S. Hietala, S. Strandman, P. Jarvi, M. Torkkeli, K. Jankova, S. Hvilsted and H. Tenhu,

Macromolecules 42 (2009), p. 1726.

[4] N. Morimoto, Y. Sasaki, K. Mitsunushi, E. Korchagina, T. Wazawa, X.-P. Qiu, S.-i. M.

Nomura, M. Suzuki and F. M. Winnik, Chem. Commun., 5 (2014) p. 8350.

[5] C. Herfurth, A. Laschewsky, L. Noirez, B. von Lospichl, M. Gradzielski, Polymer 107 (2016),

p. 422.

87

SA5 - Self-Assembled Phage-Based Colloids for High Localized Enzymatic

Activity Mariana Alarcón-Correa1, Jan-Philipp Günther1,2, Jonas Troll1, Vincent Mauricio Kadiri1,2, Joachim

Bill3, Peer Fischer1,2 and Dirk Rothenstein3

1 Micro, Nano and Molecular Systems Lab, Max Planck Institute for Intelligent Systems, Stuttgart,

Germany 2 Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart,

Germany 3 Institute for Materials Science, University of Stuttgart, Heisenbergstrasse 3, 70569 Stuttgart,

Germany

Catalytically active colloids are model systems for chemical motors and active matter. It is desirable

to replace the inorganic catalysts and the toxic fuels that are often used, with biocompatible enzymatic

reactions. However, compared to inorganic catalysts, enzyme-coated colloids tend to exhibit less

activity, partially because the immobilization of enzymes to inorganic supports often reduces the

turnover rate of the enzymes [1]. In contrast, supports made from proteins represent a superior micro-

environment for the immobilization of enzymes and permit the specific binding [2]. Nevertheless,

magnetic colloids can facilitate the recovery of the (biological) catalyst if it is bound to it.

We developed a novel, catalytically active micro system based on enzymes coupled to the surface of

magnetic inorganic colloids via self-assembled genetically engineered M13 bacteriophages (E-P-C).

This results in a highly active bioreactor, which ensures high and localized enzymatic activity. The

magnetic properties of the carrier particle allow for repeated enzyme recovery from a reaction

solution, while the enzymatic activity is retained in all the cycles.

Furthermore, localizing the colloidal bioreactors with a magnetic field in a micro container that

contains the enzyme substrate creates a fluid flow inside the chamber. The system here developed,

shows the fastest fluid flow reported to date by a biocompatible enzymatic micro pump. In addition,

it is functional in complex media including blood where the enzyme driven micro pump can be

powered at the physiological blood-urea concentration [3].

Figure 1. a) Schematic representation of the E-P-C. b) Enzymatic micro pumps constructed with E-

P-Cs.

[1] C. García-Galán, Á. Berenguer-Murcia, R. Fernández-Lafuente, R. C. Rodríguez, Adv. Synth.

Catal. 2011, 353, 2885–2904.

[2] C. Koch, K. Wabbel, F. J. Eber, P. Krolla-Sidenstein, C. Azucena, H. Gliemann, S. Eiben, F.

Geiger, C. Wege, Front. Plant Sci. 2015, 6, DOI 10.3389/fpls.2015.01137.

[3] Mariana Alarcón-Correa, Jan-Philipp Günther, Jonas Troll, Vincent Mauricio Kadiri, Joachim

Bill, Peer Fischer , and Dirk Rothenstein, ACS Nano (2019). Just Accepted DOI:

10.1021/acsnano.9b01408

88

SA6 - Chemically powered colloids that self-assemble Tingting Yu†1,2, Prabha Chuphal†3, Snigdha Thakur3, Shang Yik Reigh1, Dhruv P. Singh1, and Peer Fischer1,2

1Max Planck Institute for Intelligent Systems, Stuttgart, Germany 2Institute for Physical Chemistry, University of Stuttgart, Stuttgart, Germany 3Department of Physics, Indian Institute of Science Education and Research Bhopal, India Self-propelling colloids, which are also known as chemical motors, rely on an asymmetric distribution of substrate or product molecules for propulsion. The chemical fields around such a catalytically active particle can – in addition to propulsion – give rise to phoretic interactions with other motors or colloids. Under the right conditions an attractive potential generated by a spherical catalytically-active colloid can attract nearby passive colloids. The active-passive dimer then naturally self-assembles and because of its symmetry broken structure can give rise to self-propulsion, even though the particles in isolation show no active propulsion. The poster describes the conditions under which isotropic titanium dioxide microspheres show attractive interactions with isotropic passive silica or polystyrene spheres in a 2% hydrogen peroxide solution. Because the TiO2 is a semi-conductor, light can be used to switch the interactions on and off. The assembly and the active motion of the dimer motor can then be remotely controlled by the illumination conditions. Computer simulations show good agreement with experimental results and observations [1][2].

Figure 1. The chemically active (black) and passive (white) particles are non-motile when light is off but they form a self-propelling dimer when the light is on.

[1] T. Yu, P. Chuphal, S. Thakur, S. Y. Reigh, D. P. Singh, and P. Fischer, Chem. Commun., 54, 84, pp. 11933–11936, (2018). [2] The authors acknowledge funding from the DFG (Projektnummer 253407113 under the SPP program 1726) and the Max Planck Society. The computational work was carried out at the HPC facility in IISER Bhopal, India.

89

SP1 - How promoting and breaking of intersurfactant H-bonds impact on foam

stability

Tamara Schad1, Natalie Preisig1, Leandro Jacomine2, Romain Bordes3, Cosima Stubenrauch1

1 Universität Stuttgart, Institut für Physikalische Chemie, Pfaffenwaldring 55, 70569 Stuttgart, Germany 2 Institut Charles Sadron, 23 rue du Loess, 67037 Strasbourg, France 3 Chalmers University of Technology, Department of Chemistry and Chemical Engineering, Applied Chemistry, SE-41296, Göteborg, Sweden

Based on previous results revealing that intersurfactant H-bonds improve foam stability [1], we now focus on how foams stabilized by two different N-acyl amino acid surfactants, namely sodium N-lauroyl sarcosinate (C12SarcNa) and sodium N-lauroyl glycinate (C12GlyNa), are affected by different additives. The chosen surfactants differ by one methyl group at the nitrogen of the amide bond that blocks intersurfactant H-bonds in case of C12SarcNa (Figure 1). The additives used were NaF, NaCl, NaSCN, glycerol, and urea, as they influence the formation of H-bond networks in different ways. The salts were chosen because they are cosmotropic (NaF), chaotropic (NaSCN), and in between (NaCl) [2], while glycerol and urea were chosen as they act as competitors to H-bond donor groups [3,4]. Surface tension measurements showed that C12GlyNa is more tightly packed than C12SarcNa in absence of additives. The addition of salts decreased the cmcs of both surfactants and increased the packing density, with the areas per head group being systematically smaller for C12GlyNa. The effect of the additives on foam stability was studied by image analysis of the foam structure and by foam height measurements. The salts had no effect on foams stabilized by C12SarcNa, while the stability of foams stabilized by C12GlyNa followed the trend NaF > NaCl > NaSCN. On the other hand, glycerol and urea decreased the stability of foams stabilized by C12GlyNa, while these additives did not affect the stability of foams stabilized by C12SarcNa. This study provides new insights into the importance of H-bond promoters and breakers, which should be used in the future design of tailor-made surfactants.

Figure 1. Structure of the surfactants (left) sodium N-lauroyl sarcosinate (C12SarcNa) and (right) sodium N-lauroyl glycinate (C12GlyNa). The intersurfactant H-bond between two C12GlyNa molecules is also shown.

[1] C. Stubenrauch, M. Hamann, N. Preisig, V. Chauhan, R. Bordes, Advances in Colloid andInterface Science, 247 (2017), p. 435[2] Y. Zhang, P. S. Cremer, Current Opinion in Chemical Biology, 10 (2006), p. 658[3] W. J. Xie, Y. Q.Gao, J. Phys. Chem. Lett., 4 (2013), p. 4247[4] W. K. Lim, J. Rösgen, S. W. Englander, PNAS, 106 (8) (2009), p. 2595.

90

SP2 - Understanding interactions in non-aqueous thin liquid films

Tetiana Orlova1, Robin Bollache1, Pierre Muller1, Patrick Kekicheff1, Natalie Preisig2, Cosima

Stubenrauch1,2 and Wiebke Drenckhan1

1 Institut Charles Sadron, Université de Strasbourg, 23 rue du Loess, 67034 Strasbourg, France. 2 Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart,

Germany.

Liquid foams consist of gas bubbles which are dispersed in a continuous liquid phase. Being

thermodynamically unstable systems, foams need to be kinetically stabilised by surface active

agents (surfactants). The most investigated types of liquid foams are aqueous foams due to their

wide-spread use in industry, ranging from pharmacy, healthcare and food to detergency or fire-

fighting. Foams produced from non-aqueous fluids are much less studied, although they play an

important role in many areas such as oil recovery or polymer foam manufacturing. Despite the

importance of liquid foams, their stability is still poorly understood. While our understanding of the

fundamental mechanisms playing a role in aqueous foams has advanced quite significantly [1, 2],

many basic questions regarding the stability of non-aqueous foams await clarification [3].

Since a major control factor of foam stability is the stability of the thin liquid films separating the

gas bubbles, we propose here an in-depth investigation of individual, free-standing liquid films of a

set of model systems. Using different surfactants (-C12G2, C12E6, and a siloxane-based block

copolymer) and different polar, non-aqueous solvents, we attempt to understand how the solvent

affects the static and dynamic interactions in thin liquid films, which we measure with a Thin-Film

Pressure Balance [4]. The solvation of surfactant molecules with molecules other than water is of

particular interest for our study because the effect of hydration on the stability of aqueous thin

liquid films has been elucidated [5] and thus a comparison between “hydration with water” and “solvation with a polar molecule other than water” is of utmost importance for the understanding of the interactions in non-aqueous thin liquid films [6].

[1] D Langevin in “Encyclopedia of Surface and Colloid Science”, ed. P Somasundaran, (CRC

Press), p. 2837.

[2] E Rio and A-L Biance, ChemPhysChem 15 (2014), p. 3692.

[3] A-L Fameau and A Saint-Jalmes, ACIS Supplement C 247 (2017), p. 454.

[4] C Stubenrauch and R von Klitzing, J. Phys.: Condens. Matter 15 (2003), p. R1197.

[5] P M Claesson, M Kjellin, O Rojas and C Stubenrauch, PCCP 8 (2006), p. 5501.

[6] The authors acknowledge funding from the USIAS project “Interactions in thin liquid films:

towards non-aqueous foams, emulsions & dispersions”.

91

SP3 - Foam film properties of NaPSS/C14TAB-mixtures: Influence of added Salt

Kevin Gräff1, Larissa Braun1, Regine von Klitzing1

1 Technische Universität Darmstadt, Soft Matter at Interfaces, Darmstadt, Germany

The properties of foams are of interest in many applications such as food technology, firefighting,

in personal care products and in industrial separation processes such as flotation1.

Investigation of the single building blocks of foams, the so-called foam films that separate the air

bubbles from each other, is a key to understand the properties of macroscopic foam2.

Due to the formation of highly surface-active complexes, mixtures of oppositely charged

polyelectrolytes and surfactants are widely used in many industrial applications.

These surface-active complexes show many different properties, depending on their components,

the ratio of the components and the surrounding properties such as pH values2. Especially the

change in conformation is interesting, because this might be a factor that affects the surface-activity

of the complexes.

There exist many studies1,2,3 that focus on a wide range on different surfactants and different

polyelectrolytes and their ratios. However, the influence of the ionic strength – especially on the

foam films – is still unclear.

In this work, we use a thin film pressure balance (TFPB) to study the foam films of

NaPSS/C14TAB-mixtures in terms of the disjoining pressure inside the foam films, the surface

potential at the air/water interface and the foam film stability. We add NaBr (the combination of the

two counterions) to get insights on the influence of the ionic strength on the foam film properties.

Our current investigation shows an unexpected increase in foam film stability with increasing NaBr

concentration, which might be explained by a change of the conformation of NaPSS at the air/water

interface.

[1] Bureiko, A. et al., Current applications of foams formed from mixed surfactant– polymer

solutions; Advances in Colloid and Interface Science 222 (2015) 670–677 Contents

[2] Uhlig, M et al., Surface adsorption of sulfonated poly(phenylene sulfone)/C14TAB mixtures

and its correlation with foam film stability; Phys.Chem.Chem.Phys., 2016, 18,18414

[3] Kristen, N. et al., No Charge Reversal at Foam Film Surfaces after Addition of Oppositely

Charged Polyelectrolytes?; J Phys Chem B 2009;113:7986

92

SP4 - A combined Surface Tension / Neutron Reflectometry study of the salt

impact on oppositely charged Polyelectrolyte/Surfactant-mixtures

L. Braun1 and Regine v. Klitzing1

1Department of Physics, Soft Mater at Interfaces, Technische Universität Darmstadt, Darmstadt,

Germany

The surface properties of oppositely charged polyelectrolyte/surfactant mixtures play an important

role in colloidal dispersions (foams, emulsions) e.g. for cosmetics, cleaning products and in food

technology [1].

Extensive research on such mixtures was already performed with the focus on different

polyelectrolytes as well as surfactants [2]. However, the influence of the ionic strength is still

unclear.

This work focuses on the influence of added salt (NaBr or LiBr depending on the polyelectrolyte

counterion) on the adsorption behaviour of mixtures of the anionic polyelectrolyte NaPSS or

sPSO2-220 with the cationic C14TAB. Therefore, surface tension measurements were performed

with a fixed C14TAB concentration and a variable polyelectrolyte concentration at different salt

concentrations (10-4, 10-3, 10-2 M).

For both systems, we find a steep increase of the surface tension around the bulk stoichiometric

mixing point (BSMP) due to a loss of surface activity. Addition of salt reduces the surface tension

over the whole studied polyelectrolyte concentration range (10-5 – 10-3 monoM) for NaPSS and

broadens the observed increase. In contrast, salt reduces the surface tension of sPSO2-220 only

above the BSMP while the steepness of increase is unaffected. This non-monotonous behaviour in

surface tension is a hint for at least two counteracting effects, which will be discussed.

These findings will be correlated the surface excesses of both compounds which can be separated

from each other by neutron reflectometry measurements. [3]

[1] B. Lindmann, F. Antunes, S. Adarova, M. Miguel, T. Nylander, Colloid Journal, 2014, 76, 585-

594.

[2] N. Kristen, A. Vüllings, A. Laschewsky, R. Miller, R. v. Klitzing, Langmuir, 2010, 12, 9321-

9327.

[3] The authors acknowledge funding from DFG.

93

SP5 - Memory effects in polymer brushes showing co-nonsolvency effects

Simon Schubotz, Petra Uhlmann, Andreas Fery, Günter K. Auernhammer

Leibniz Institute of Polymer Research, 01069 Dresden Germany

Some polymer brushes show the surprising co-nonsolvency effect: They collapse in a mixture of two

good solvents at some specific mixing ratio. Recent studies focused previously on the response of

brushes which entirely covered by a liquid [1]. Here, we concentrate on partial wetting of co-

nonsolvent polymer brushes, i.e., on the dynamics of a three-phase contact line moving over such

brushes. We demonstrate that the wetting behavior depends on the wetting history of the polymer

brush. This memory of the brushes is a very interesting property if you want to create “smart” materials.

We use Poly(N-isopropylacrylamide) (PNiPAAm) brushes and water and ethanol as good solvents.

In water/ethanol mixtures, the brush thickness is a non-monotonous function of the ethanol

concentration [1]. We are investigating how different ethanol concentrations change the memory

effect generated by subsequent drops. Since the brush is also in contact with the atmosphere which

can induce swelling, we are also controlling the water (and ethanol) concentrations in the atmosphere.

Figure 1 shows the advancing contact angle of drops successively deposited on the same spot versus

the respective drop radius. First, drop 1 was placed and removed; then, drop 2 was placed and

removed; etc. There is a clear difference of advancing contact angles on between previously wetted

and dry areas of the substrate. In the contribution, we discuss the effects of timescales, composition

of the drop and the surrounding atmosphere, as well as the brush thickness.

[1] Yong, Huaisong et al., (2018). Cononsolvency Transition of Polymer Brushes: A Combined

Experimental and Theoretical Study. Materials. 11. 991. 10.3390/ma11060991.

Figure 1: The memory of brushes on consecutively deposited drops 1-3. Previously deposited

drops induce swelling of the brush that modifies the wetting behavior (advancing contact angle)

of subsequent drops. The liquid compositions (water/ethanol) were 20/80 (left) and 40/60 (right).

The measurements were conducted at 50% relative humidity and 23 ºC.

94

SP6 - Influence of charges on the behavior of microgels at oil-water interfaces

Maximilian M. Schmidt1, Steffen Bochenek1, Walter Richtering1

1 Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany

Microgels are crosslinked polymeric networks swollen in a good solvent that can adjust their

properties and size towards external stimuli. Moreover, they are highly interfacial active and thus

suitable for application as responsive emulsifiers [1].

The role of electrostatics on the properties of polyelectrolyte microgels adsorbed at air-water and

oil-water interfaces has recently been investigated by means of Langmuir trough experiments. Yet

results are apparently inconsistent regarding the influence of the microgel charge density on its

compressibility [2,3].

In our work we set out to clarify the dissimilar observations and further elucidate the effect of

charges on the behavior of microgels at oil-water interfaces. To this aim we used a Langmuir trough

setup to study the effect of pH and ionic strength of the aqueous subphase on the compression of N-

isopropylacrylamide-based microgels with ionizable comonomers. Our results show that for smaller

microgels there is a difference in the compressibility at pH values at which the microgel is charged

compared to the uncharged state (Fig. 1a). Whether this is solely linked to the interfacial properties

of the microgel or may also be related to a potentially diminished ability of charged microgels to

adsorb at the interface in the first place is currently under evaluation. Modulation of the Debye

length by adjustment of the ionic strength reverses the effect of pH. In contrast, for larger microgels

but with similar amount of ionizable comonomer we observe no significant difference in the

compression isotherms regardless of the solution pH (Fig. 1b). Simultaneously to compression of

the interface, monolayers were transferred onto solid substrates and analyzed via atomic force

microscopy (Fig. 1c and d). The evolution of the microstructure of the monolayer upon compression

was evaluated in terms of their two-dimensional phase behavior.

Figure 1. Normalized Langmuir compression isotherms of (a) smaller and (b) larger polyelectrolyte

microgels (aqueous subphase is always 0.1 mM KCl solution, while decane is used as oil phase)

and AFM micrographs of the smaller microgel deposited onto silica substrates at similar surface

pressures at (c) pH 3 and (d) pH 9 (height images, scale bar equals 1 µm).

[1] W. Richtering, Langmuir 2012, 28, 17218-17229.

[2] K. Geisel, L. Isa, W. Richtering, Angew. Chem. Int. Ed. 2014, 53, 4905-4909.

[3] C. Picard, P. Garrigue, M.-C. Tatry, V. Lapeyre, S. Ravaine, V. Schmitt, V. Ravaine, Langmuir

2017, 33, 7968-7981.

[4] The authors thank the Deutsche Forschungsgemeinschaft for financial support within the

collaborative research center SFB 985 “Functional Microgels and Microgel Systems” (Project B8).

(a) (b) (c) (d)

95

SP7 Controlling the collapse of microgels in confinement by adsorption process

M. Friederike Schulte1,2, Andrea Scotti1, Monia Brugnoni1, Steffen Bochenek1, Ahmed Mourran2,

Walter Richtering1,2

1 Institute of Physical Chemistry, RWTH Aachen University, Aachen, Germany 2 DWI – Leibniz Institute for Interactive Materials, Aachen, Germany

PNIPAM microgels are thermo-responsive and combine the properties of flexible polymers and

hard colloids. Depending on the cross-linker amount incorporated in the microgel network one of

these characters is dominating. [1] In addition, microgels are highly interfacial active, even though

not being amphiphilic. The adsorption to the interface is accompanied by microgel deformation, due

to a balance between the maximization of the adsorption energy and the restriction by the elasticity

of the network. [2,3]

We studied two very different microgels in terms of cross-linker content, (i) 5 mol% cross-linked,

and (ii) ultra-low cross-linked (ULC) PNIPAM microgels. The collapse in bulk solution of these

microgels is similar as shown by static light scattering (SLS) and small-angle neutron scattering

(SANS) measurements. However, atomic force microscopy (AFM) measurements revealed that the

confinement of the microgels at the solid interface leads to strongly different behaviors. While

5 mol% crosslinked microgels always collapse into smooth half ellipsoids, the ULC microgels do

not have one collapsed morphology. The final balance between adsorption energy and network

elasticity can be trapped in two different states, depending on the adsorption process. On one hand,

the polymeric character is dominating when ULC microgels are deposited via spin-coating and only

single polymer chains collapse into globules, whereas on the other hand, directly adsorbed ULC

microgels are restricted in their deformation and collapse into homogenous half ellipsoids as

regularly crosslinked microgels. One and the same microgel can be used to obtain strongly different

surface topographies by the choice of the adsorption process [4].

Figure 1. AFM height images of the same ULC microgels collapsed at a solid interface, but

adsorbed via two different pathways; spin-coating (left) and direct adsorption (right).

[1] A. Mourran, Y. Wu, R. A. Gumerov, A. A. Rudov, I. I. Potemkin, A. Pich, M. Möller,

Langmuir, 32, 2016, 723-730.

[2] M. Destribats, V. Lapeyre, M. Wolfs, E. Sellier, F. Leal-Calderon, V. Ravaine, V. Schmitt,

Soft Matter, 7, 2011, 7689-7698.

[3] O. S. Deshmukh, A. Maestro, M. H. G. Duits, D. van den Ende, M. C. Stuart, F. Mugele,

Soft Matter, 10, 2014, 7045-7050.

[4] The authors acknowledge the Deutsche Forschungsgemeinschaft (DFG) for financial support

within the Sonderforschungsbereich SFB 985 “Functional Microgels and Microgel Systems”.

96

SP8 - Pressure Dependent Structural Evolution of Poly(N-isopropylacrylamide)

Mesoglobules above Cloud Point Geethu P. Meledam1, Bart-Jan Niebuur1, Vitaliy Pipich2, Marie-Sousai Appavou2, Alfons Schulte3, and Christine M. Papadakis1

1TU München, Physik-Department, Garching, Germany 2FZ Jülich, JCNS at MLZ, Garching, Germany 3University of Central Florida, Orlando, U.S.A. The thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPAM) in aqueous solutions forms stable mesoglobules when it is heated above the cloud point (TCP). The further growth and coalescence of these dehydrated mesoglobules are hindered by the viscoelastic effect [1]. High-pressure measurements provide a way to enhance the degree of hydration of PNIPAM mesoglobules since the compressibility as well as the clathrate-like ordered structure of water around the hydrophobic groups are significantly affected by the application of pressure. Indeed, the increased hydration of mesoglobules further lead to modifications in their surface structure and growth processes [2]. We report the influence of pressure on the structural evolution of PNIPAM mesoglobules above the cloud point investigated using very small angle neutron scattering (VSANS). The representative VSANS profiles of a 3 wt % PNIPAM solution in D2O measured at different pressures at a temperature, T=38°C (T>TCP) is displayed in Figure 1 (a). The radius of gyration of the mesoglobules (Rg) obtained by fitting the VSANS profiles with the Beaucage model [3], as a function of pressure is portrayed in Figure 1 (b). At a critical pressure, the size of the mesoglobules increases markedly, and this critical pressure is found to depend on temperature. We presume that the pressure induced structural evolution in PNIPAM mesoglobules are due to the pressure dependent hydration followed by the aggregation of mesoglobules. Further, the growth process of the PNIPAM mesoglobulesis highly correlated to the thermal history of the PNIPAM solution.

Figure 1. (a) Representative VSANS data of a 3 wt % PNIPAM solution in D2O measured at different pressures ranging from 10-110 MPa and at a temperature of 38°C. (b) Radius of gyration of the mesoglobules (Rg) as a function of pressure. [1] B.-J. Niebuur et al., ACS Macro Lett. (2018) 1155. [2] B.-J. Niebuur et al., ACS Macro Lett. (2017) 1180. [3] G. Beaucage et al., J. Non-Cryst. Solids (1994) 797.

97

SP9 - Thermal Behavior and Cononsolvency of the Amphiphilic Diblock

Copolymers PMMA-b-PNIPAM and PMMA-b-PNIPMAM in Aqueous Solution Chia-Hsin Ko1, Cristiane Henschel2, Lester C. Barnsley3, Jia-Jhen Kang1, André Laschewsky2,4,

Peter Müller-Buschbaum1, Christine M. Papadakis1 1 Physics Department, Technical University of Munich, Garching, Germany 2 Institut für Chemie, University of Potsdam, Potsdam-Golm, Germany 3 Forschungszentrum Jülich, JCNS at MLZ, Garching, Germany 4 Fraunhofer Institute for Applied Polymer Research IAP, Potsdam-Golm, Germany

Amphiphilic diblock copolymers having a hydrophobic poly(methyl methacrylate) (PMMA) block

and a thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) block or a poly(Nisopropyl-

methacrylamide) (PNIPMAM) block form core-shell micelles in aqueous solution. The transition

temperature of the PNIPMAM block is 43 oC, thus significantly higher than the one of PNIPAM (32 oC), which has been attributed to steric hindrance by the additional methyl group weakening the

intermolecular interactions [1]. Therefore, the collapse and aggregation behavior of PMMA-b-

PNIPMAM are of special interest. Both, the PNIPAM and PNIPMAM blocks, are not only sensitive

to temperature, but also to the solvent composition. Adding methanol as a cosolvent causes these

blocks to collapse which reduces the transition temperature, i.e. cononsolvency is observed [2, 3].

However, PMMA features the cosolvency effect in water-methanol mixtures, i.e. the hydrophobicity

of PMMA block is reduced by adding the cosolvent methanol [4].

We focus on investigating (i) the structure of the self-assembled micelles and the changes upon

collapse and aggregation with increasing temperature, and (ii) the cononsolvency and cosolvency

effect of PMMA-b-PNIPAM and PMMA-b-PNIPMAM in pure D2O and in different D2O/CD3OD

mixtures using turbidimetry, differential scanning calorimetry (DSC), dynamic light scattering

(DLS) and small-angle neutron scattering (SANS, Figure 1a). The results reveal the role of the nature

of the thermoresponsive block on the thermal behavior and the morphology changes upon

temperature and solvent composition (Figure 1b).

Figure 1. (a) Small-angle neutron scattering curves of a 50 g/L PMMA22-b-PNIPMAM260 solution

in D2O. (b) Schematic representation of the thermal behavior.

[1] E. I. Tiktopoulo et al., Macromolecules 28 (1995), 7519–7524

[2] F.M. Winnik, H. Ringsdorf, J. Venzmer, Macromolecules 23 (1990), 2415-2416.

[3] M. J. A. Hore et al., Macromolecules 46 (2013), 7894–8901.

[4] R. Hoogenboom et al, Aust. J. Chem. 63 (2010), 1173–1178.

[5] This project is funded by Deutsche Forschungsgemeinschaft DFG.

98

SP10 - Transparent Microparticles in Water/Sucrose Solution

Payam Payamyar 1,2

1 Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstr. 1, 40225

Düsseldorf, Germany 2 Harvard John A. Paulson School of Engineering and Applied Sciences, 9 Oxford Street,

Cambridge, MA 02138, United States

The refractive index of water (~1.334) is lower than most of the colloidal particles used in soft

matter research, making their respective aqueous dispersions turbid in visible light. Even in dilute

conditions, this can impose limitations on light-based analytical techniques in accessing structural

or dynamic information from the particles, for studies like microparticle transport in water, drying

of water-based paints, the interaction of water with superhydrophobic surfaces, as well as self-

assembly of DNA coated colloids. Yet, water serves as an important dispersion medium for a

variety of colloids with biological or technological relevance where visualization can be beneficial.

In this work, a facile, one step dispersion polymerization of heptafluoro-n-butyl methacrylate

(7FbM) is shown to provide microparticles that can be made transparent in the bio-friendly medium

of water/sucrose with a refractive index of 1.3770.[1] The synthesis consists of a one-step batch

involving 7FbM monomer without the need for multiple steps of seeded growth reactions. The

procedure allows for particle purification by centrifugation rather than relying on dialysis.

Dispersions with the volume fraction of ~1% are imaged 80 µm deep into the sample using

confocal fluorescence microscope. Such particles can provide insights into (bio-)physical processes

in aqueous environments.[2]

Figure 1. Dispersion of particles in pure water with volume fraction of ~1% (A), and after

dissolution of sucrose (B), until full transparency is reached upon addition of ~0.28 g/ml sucrose,

where the sample is dyed by Rhodamine B (C).

[1] P. Payamyar, Soft Matter, 2019, 15, 4428–4431

[2] The author would like to thank Prof. Vinothan N. Manoharan (Harvard) and Prof. Frans

Spaepen (Harvard) for their valuable input and insight on this work. Fellowship funding of the

Swiss National Science Foundation (SNSF) is acknowledged.

99

SP11 - Structural investigation on PTX-loaded poly(2-oxazoline) molecular

brushes

Jia-Jhen Kang1, Dan Gieseler2, Lester C. Barnsley3, Rainer Jordan2 and Christine M. Papadakis1

1 Technical University of Munich, Physics Department, Garching, Germany 2 Dresden University of Technology, Faculty of Chemistry and Food Chemistry, Dresden, Germany 3 Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Garching, Germany

Poly(2-alkyl-2-oxazoline)s (POx) are well known for their tunable thermoresponsive properties and

good biocompatibility, which make them promising materials for biomedical applications, e.g. as

drug carriers. In the present work, three POx-based molecular brushes, featuring PMeOx-b-PBuOx

block copolymer side arms densely-grafted on a poly(methacrylic acid) backbone, are investigated

in aqueous solution. Whereas the hydrophobic PBuOx block is attached to the backbone, the

hydrophilic PMeOx block is located near the periphery of the molecular brush. This architecture is

desirable for drug delivery applications, since the PBuOx core can serve to store the hydrophobic

anticancer drug, Paclitaxel (PTX), whereas the PMeOx shell may facilitate transport in the human

body, as illustrated in figure 1.

Using small-angle neutron scattering (SANS), the inner structure of the PTX-loaded molecular

brushes with different degrees of polymerization of the backbone and the side arms was

investigated at 37 °C. The PTX/polymer weight ratio ranged from 0.1/10 to 5/10.

Assuming a PBuOx inner part and a water-rich outer part, where PMeOx is swollen in the aqueous

environment, the SANS data were successfully fitted with a core-shell ellipsoid model. It is found

that, the more PTX is loaded, the more elongated the ellipsoid becomes. The results also indicate a

critical PTX concentration, c*, where saturation of PTX in the hydrophobic core part is reached. It

is observed that the backbone length is directly proportional to c*, i.e. to the drug-loading capacity.

Initially, above c*, PTX temporarily attaches to the hydrophilic shell, but the solution forms

precipitates after about three months.

In summary, the inner structure of PTX-loaded core-shell molecular brushes is studied in

dependence on PTX concentration, disclosing the effect of the molecular architecture on the drug-

loading ability, providing hints on the optimum design of the drug carrier.

Figure 1. Illustration of the studied potential drug-delivery system: a core-shell molecular brush

with a hydrophobic inner part, where the hydrophobic Paclitaxel can be stored, and a hydrophilic

outer part to ensure the solubility in aqueous environment.

100

SP12 - Round-robin test of a surface-modified polystyrene particle suspension

based negatively charged zeta potential control

Dr. Kyriakos A. Eslahian1

1 BS-Partikel GmbH, Mainz, Germany

Properties of colloidal systems are often determined by surface properties. Receiving insight into

interactions in the particle-particle or particle-solvent interfaces is rather challenging. In order to

monitor particle surface properties the zeta potential is an easy to observe primary measure. Many

methods have been established to measure the zeta potential in a more or less reliable way.

Although the zeta potential can hardly be defined physically, availability of this parameter is well

established in quality control for all kind of colloidal applications. Thus, it is of essential interest to

establish a reliable control in order to become able comparing individual measurements with

different analytical methods and instruments. In an environment dominated by negative surface

charge commercial availability of a best possible negatively charges zeta potential is crucial.

Based on surface-modified polystyrene particles suspended in a non-surfactant aqueous

environment, we have developed a negatively charged zeta potential control with excellent

reproducibility and low background noise. Besides extended in-house analysis we have initiated an

interlaboratory comparison of zeta potential values determined by various instrument manufacturers

and academia partners.

The result of the round-robin test is presented in this study. We compare reproducibility errors with

deviations for measurements by different devices applying the same or similar analytical method.

Furthermore we determine the impact of different physical principles on measuring the zeta

potential. We discuss theoretical approaches based on the primary electroviscous effect to

understand inter method deviations [1] [2]. Also the influence of different approaches for the Henry

function are considered.

As a conclusion we expect having approached a best possible control for monitoring the zeta

potential independently of the analytical method applied.

Skip a line before each new paragraph, but do not indent paragraphs. Use left justified formatting

for the text.

[1] Mangelsdorf CS, White LR, Effects of stern-layer conductance on electrokinetic transport

properties of colloidal particles. Faraday Trans. 86(16) (1990), p2859. [2] Vorwerg L, Antonietti M, Tauer K, Electrophoretic mobility of latex particles: effect of particle

size and surface structure. Colloids and Surfaces A: Physicochemical and Engineering Aspects

150(1–3) (1999): 129–135

101

102

List of Contributors Abitaev, Karina .................................. AM2 Alapan, Yanus .................................. SL36 Alarcón-Correa, Mariana ........ AM10, SA5 Ali, Wael ............................................. SL7 Andrieux, Sébastien ........................... SL9 Anselmetti, Dario .............................. SL11 Antonietti, Markus ............................. SL20 Appavou, Marie-Sousai ........... SP8, SL12 Atanasova, Petia ............................... AM2 Auernhammer, Günter K. .................. SP5 Azeri, Özge ....................................... SA2 Ballauff, Matthias .............................. SL26 Barnsley, Lester C ......... SL21, SP9, SP11 Bartsch, Eckhard .............................. SL24 Bauhof, Jessica ................................ SL33 Bechinger, Clemens ........................... PL2 Beker, Onur ...................................... SL36 Bender, P. ........................................ SL34 Berglund, Lars .................................... SL9 Beurer, Ann-Katrin ............................ SL33 Bilalov, Azat ..................................... SL31 Bill, Joachim ............................. SA5, AM2 Binks, Bernard P. ............................. PL12 Bochenek, Steffen ........... SL19, SP6, SP7 Bollache, Robin ................................. SP2 Bordes, Romain ................................. SP1 Borkovec, Michal………………………..PL9 Bössenecker, Brigitte........................ SL18 Botin, Denis ............................ SL23, SL25 Boyaciyan, Dikran ............................. AM3 Brandl, Georg ................................... SL17 Braun, Larissa .................. AM3, SP3, SP4 Bressel, Lena ......................... SL16, SL27 Bruckner, Johanna R. ....................... SL33 Brugnoni, Monia ................ 15, SL19, SP7 Cautela, Jacopo ............................... SL30 Chiappisi, Leonardo .......................... SA2 Chuphal, Prabha ............................... SA6 Clasen, C ......................................... SL22 Clemens, Daniel ............................... SA1 Crassous, Jérôme J. ........................ SL30 Crowley, Daniel ................................ SL23 Dabrowski, Miriam ............................. AM8 Danino, Dganit.................................. SL12 Dargel, Carina .................................. SL10 Dekker, Riande................................. SL23 Del Sorbo, Guiseppe R. ...................... SL4 Demirors, Ahmet .............................. SL36 Denton, A. R. .................................... SL15 Dhont, J.K.G. .................................... SL22

Disch, Sabrina .................... ………….SL34 Drenckhan, Wiebke .............................. SP2 Eremin, Alexey ........................... SL1, SL32 Eslahian, Kyriakos A. ......................... SP12 Fery, Andreas ...................................... SP5 Fischer, Peer ......... SA5, SA6, AM10, AM11 Fischer, S. .......................................... SL24 Forg, Sandra .............................. AM5, AM9 Förster, Stephan ................................ SL35 Frielinghaus, Henrich ................. SL5, SL17 Galantini, Luciano .............................. SL30 Gallei, Markus ..................................... AM5 Garvey, Emma J. ............................... PL12 Gebhardt, Jacqueline ......................... SL33 Geisler, Ramsia.................................. SL10 Gieseler, Dan ..................................... SP11 Giesselmann, Frank ........................... SL33 Gilzer, Dominic ................................... SL11 Goett-Zink, Lukas ............................... SL11 Gradzielski, Michael ........... SA1, SA2, SA4,

SL6, SL12 Gräff, Kevin .......................................... SP3 Gröhn, Franziska ................................ SL29 Gröschel, André H .............................. PL11 Grüßer, Martin ..................................... AM1 Günther, Jan-Philipp ............................ SA5 Gutmann, Jochen S. ............................ SL7 Härk, Eneli ......................................... SL26 Hass, Roland ..................................... SL27 Hechenbichler, Michelle ....................... SA4 Heidari, Mojdeh .................................... SL2 Hellweg, Thomas ..................... SL10, SL17 Henschel, Cristiane ..................... SA4, SP9 Herbst, Michael .................................... SL9 Hériguez, Valérie .................................. PL6 Hildebrand, Viet.................................. SL28 Hillmann, Roland ................................ SL11 Hoffmann, Ingo ............................ SL4, SA1 Honecker, D. ...................................... SL34 Hörmann, Anja F. ................................... A2 Houston, J. E ..................................... SL15 Jacomine, Leandro ............................... SP1 Jakob, Franziska .................................. SL2 Jaksch, Sebastian .............................. SL17 Jordan, Rainer ................................... SP11 Jung, Falco ........................................ SL14 Jung, Florian ...................................... SL21 Kadiri, Vincent M ....................... AM10, SA5 Kang, Jia-Jhen ................ SL21, SP9, SP11 Karg, Matthias .................................... SL35

103

Kekicheff, Patrick .................................. SP2 Klocke, Jessica L. ............................... SL11 Ko, Chia-Hsin .................. SL21, SL28, SP9 Koch, Karin ......................................... SL32 Kochovski, Zdravko ..................... M4, SL26 Koetz, Joachim ................................... SL25 Kolik-Shmuel, Luba ............................ SL12 Kopera, Bernd A.F. ............................. SL35 Kottke, Tilman .................................... SL11 Kraft, Daniel J. ...................................... PL7 Kraus, Tobias ....................................... PL8 Krieger, Anja ...................................... SL29 Kühnhammer, Matthias ...................... SL13 Kundt, Matthias .................................. SL32 Kunz, Werner ....................................... PL4 Kuschnikovskiy, Dmitry ....................... SL31 Kutz, Anne .......................................... SL29 Kuzminskaya, Olga .............................. SA1 Lagerwall, Jan .................................... PL10 Lang, C. ............................................. SL22 Langevin, Dominique ............................ PL1 Laschewski, André .............. A4, SL28, SP9 Laupheimer, Michaela ......................... AM1 Lerche, D. ................................... AM6, AM7 Lettinga, M.P. ..................................... SL22 Liebig, Ferenc .................................... SL25 Lima, Michele T. ................................... SL6 Liu, Yu ................................................ PL12 Liu, Yun ................................................ SA3 Löhmann, Oliver ................................. SL13 Lu, Yan ...................................... AM4, SL26 Lucas, S. ............................................. AM7 Maqsood, Muhammad S. ..................... SL7 Marini, Giacomo ................................. SL29 Marinopoulus, Ioannis ........................ PL12 Maurer, Miriam E.J. ............................ SL35 Mayer-Gall, Thomas ............................. SL7 Medina, Lilian ....................................... SL9 Mei, Shilin .................................. AM4, SL26 Meledam, Geethu P. ............................ SP8 Miksch, Cornelia ................................ AM10 Mitsos, Alexander ............................... SL14 Mourran, Ahmed ................................... SP7 Muller, Pierre ........................................ SP2 Müller-Buschbaum, Peter ...........SL28, SP9 Murty, Nikhilesh ................................. AM11 Niebuur, Bart-Jan ................................. SP8 Nizardo, Noverra M. ........................... SL28 Nutz, Fabian A.................................... SL35 Olsson, Ulf ............................................ SA3 Orlin, Velev D. ...................................... PL5 Orlova, Tetiana ..................................... SP2

Palberg, Thomas ...................... SL23, SL24 Panteli, Panayiota A. .......................... SL21 Papadakis, Christine M. .. SL21, SL28, SP8,

SP9, SP11 Patrickios, Costas S. .......................... SL21 Payamyar, Payam .............................. SP10 Paydar, Hanih ..................................... AM1 Peter, Florian R. ................................ AM10 Pipich, Vitaliy ........................................ SP8 Plamper, Felix A. ................................ SL14 Plüisch, Claudia S. ............................. SL18 Popescu, Mihail N. ............................... SL3 Potemkin, I. I. ..................................... SL15 Prause, Albert ...................................... SA4 Preisig, Natalie ............................ SP1, SP2 Qawasmi, Yaseen ............................... AM2 Qiu, Tian ........................................... AM10 Quan, Ting ......................................... SL26 Reich, Oliver ............................ SL16, SL27 Reigh, Shang Y. ................................... SA6 Retsch, Markus .................................. SL35 Richtering, Walter .... SL15, SL19, SP6, SP7 Rios, Camila H. .................................. PL10 Ritzert, Philipp .................................... .AM3 Rodriguez, L. ....................................... AM7 Rothenstein, Dirk .................................. SA5 Salonen, Anniina .................................. PL3 Schad, Tamara .................................... SP1 Schaertl, N. ........................................ SL24 Schlander, Annika ............................... AM5 Schlappa, Stephanie .......................... SL27 Schmid, Andreas J. ............................ SL17 Schmidt, Annette M. ........................... SL32 Schmidt, Claudia ................................ SL31 Schmidt, Maximillian M. ........................ SP6 Schmitt, Véronique ............................... PL6 Schneck, Emanuel ............................... SL4 Schneider, Harald .............................. SL17 Schneider, Sabine .............................. SL14 Schomäcker, Reinhard ................ AM5, SL6 Schönfeld, Dennis ................................ SA2 Schöttle Christian ................................ AM1 Schrader, Tobias ................................ SL17 Schubotz, Simon .................................. SP5 Schulte, Alfons ..................................... SP8 Schulte, Friederike M. .......................... SP7 Schweinfurth, Holger .......................... SL23 Schweins, Ralf ......................... SL15, SL29 Scotti, Andrea .................. SP7, SL15, SL19 Shabani, Valbone ................................. SL7 Silvi, Luca............................................ AM3 Singh, Dhruv P. ......................... AM11, SA6

104

Sitti, Metin .......................................... SL36 Sobisch, T. ................................. AM6, AM7 Soltwedel, Olaf. ................................... AM3 Sottmann, Thomas. ........... AM1, AM2, SA3 Spiering, Vivian J. ................................. SL6 Stasse, Margot ..................................... PL6 Stehl, Dmitrij ........................................ AM5 Stelling, Christian ............................... SL35 Stenqvist, Björn .................................. SL30 Stock, Sebastian ................................. AM5 Strey, Reinhard .................................... SA3 Stubenrauch, Cosima ........ AM8, SL9, SP1,

SP2 Stuckert, Rouven ................................ SL18 Swager, Timothy M. ........................... SL20 Thakur, Snigdha ................................... SA6 Traa, Yvonne ...................................... SL33 Troll, Jonas ........................................... SA5 Tseng, Shih-Yu..................................... SA3 Tsitsilianis, Constantinos .................... SL21 Uhlmann, Petra .................................... SP5 Usoltseva, A. ....................................... AM7 Vandenabeele, C. ................................ AM7 Varytimiadou, S. .................................. AM8 Vasquez, Daniela ............................... SL16 Venzmer, Joachim ................................ SL8 Viefhues, Martina ............................... SL11 Vishnevetskaya, Natalya S. ................ SL28 Voigtländer, Kathrin ............................ SL12 von Klitzing, Regine .......... AM9, AM3, AM5,

SL2, SL13, SP3, SP4 von Lospichl, Benjamin ......................... SA4 von Rülling, Florian ............................... SL1 Walker, Debora ................................. AM10 Weber, Ariane ..................................... AM5 Wenzl, Jennifer................................... SL23 Wernet, M ........................................... SL24 Wittemann, Alexander ........................ SL18 Wu, Zhiguang .................................... AM10 Xie, Dongjiu ......................................... AM4 Yigit, Berk ........................................... SL36 Yu, Tingting .......................................... SA6 Zákutná, D .......................................... SL34 Zeininger, Lukas ................................. SL20 Zhang, Mingming ................................ SL12 Zika, Alexander .................................. SL29

105

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Notes

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