Complex Fluids Design Consortium (CFDC)

www.mrl.ucsb.edu/cfdcOverview and Update

University of California at Santa Barbara

February 2, 2009

CFDC Annual Meeting Agenda – 2/2/2009 – Morning Session

9:00-9:30 Welcome and Update (Glenn Fredrickson, Director, CFDC)9:30-10:00 Two Modes of Energy Dissipation in Heterogeneous Polymeric Materials with Lossy Interfaces (Andrei Gusev, ETH)10:00-10:30 Coffee Break10:30-11:00 Mesotek – Perspectives and Future Directions (Eric Cochran, Iowa State U.)11:00-11:30 Design of Thermoplastic Elastomers: Radial (ABA)nand A(BA)n Miktoarm Architectures (Nate Lynd, UCSB)11:30-12:00 Supratelechelics: Thermoreversible Bonding in Difunctional Polymer Blends (Richard Elliott, UCSB)12:00-1:00 Lunch – 3rd Floor MRL patio

CFDC Annual Meeting Agenda – 2/2/09 – Afternoon Session

1:00-1:30 Phase Behavior in Nanoparticle/Polymer Thin Films from Fluids Density Functional Theory (Amalie Frischknecht, Sandia National Labs)1:30-2:00 Systematic Coarse-Graining of Fluid Field Theories (Mike Villet, UCSB)2:00-2:30 Numerical Methods for Polymer Brushes Using Self-Consistent Field Theory(Tanya Chantawansri, UCSB)2:30-2:45 Molecular Dynamics Simulation of Entangled Polymer Melts Based on the Continuous Chain Model (Aruna Mohan, UCSB)2:45-3:15 Coffee Break3:15-3:45 Simulations of Reversible Polymer Networks (Rob Hoy, UCSB)3:45-4:15 Study of Block Copolymer Lithography Using SCFT (Su-mi Hur, UCSB)4:15-4:30 Conformational Characteristics of a Single Polyzwitterionic Chain: Effect of Salt (Rajeev Kumar, UCSB)4:30-5:00 Field-Theoretic Simulations of Complex Coacervates (Debra Audus, UCSB)5:00-5:15 Mean Field Model of Self-Assembling Lipid Membranes with Embedded Proteins (Kang Chen, UCSB)5:15 Wrap-up, close CFDC meeting5:15-6:00 CFDC Steering Committee Meeting (Members Only, Rm 3117D MRL)

CFDC Dinner – 7pm Flavor of India —sign up at break

What is the CFDC?The Complex Fluids Design Consortium is an academic-industrial-national laboratory partnership aimed at developing computational tools for:

Designing soft materials at equilibrium, including polymer alloys and complex fluid formulationsAnalyzing the coupled flow, microstructure, and processing behavior of multiphase complex fluids

What do we hope to accomplish?

To create a suite of models, theoretical approaches, numerical methods, and software that:

Can be shared among the members of the consortiumCan be applied to address materials design problems and complex fluid processing problems of collective or individual interest

Objectives -- continuedCreate a world-class center for complex fluid and soft materials modelingEnhance interactions among the academic, industrial, and national lab partners and pool funding for supporting research projects of mutual interestCreate employment opportunities for the students and post-docs of the consortium

Organization and Partnership Model

UCSB is focal point for the CFDCCFDC “Steering Committee” will guide collective research agendaAcademic partners will contribute:

Time and expertiseAccess to graduate students and postdocsFunding though group grants

National lab partners will contribute:Time and expertiseAccess to computational facilitiesFunding though group grants, and/or DOD/DOE programs

Partnership Model -- continued

Industrial partners will contribute:Staff timeComputational resourcesFunding

As a sustaining member (shared project)As a full member (dedicated project)

UCSB ParticipantsGlenn Fredrickson, Chem. Engr. & Materials (Polymer physics, field theory, mesoscopic simulations)Hector Ceniceros, Mathematics (Numerical methods, multiscale PDEs, computational fluid mechanics)Carlos Garcia-Cervera, Mathematics (Numerical methods, stochastic PDEs)Edward J. Kramer, Materials & Chem. Engr. (Polymer physics experiment, diffusion, interfaces, mechanical properties)Others, as per interest

National Lab ParticipantsLANL

Paul Welch (MD, multiscale simulations)Kim Rassmussen (SCFT, multiscale simulations)

SNLAmalie Frischknecht (Density functional theory, PRISM)Gary Grest (MD, MC of polymers)

Other Academic CollaboratorsAndrei Gusev, Materials, ETH Zurich

Finite element methodsComposite media modeling (Mechanical, transport, and optical properties)

Eric Cochran, Chemical Engineering, Iowa StateSCFT theory, algorithms, and softwareExperimental polymer physics

David Wu, Chemistry and Chemical Engineering Depts., Colorado School of Mines

Molecular simulationsPRISM

Industrial Partners 09-10Arkema Chemicals (Full) ?Mitsubishi Chemical (Sustaining) ?Rhodia (Sustaining) ?Dow Chemical (Full) ?Nestle Research Center (Full) ?Kraton Polymers (Full)?DSM (Full)Accelyrs (Sustaining)

Possible new members: Michelin, Intel, Micron, IBM

CFDC Steering Committee 2/09

Jun Endou (Mitsubishi)Chris Roger (Arkema)Magali Charlot (Rhodia)Raffaele Mezzenga (Nestle)Valeriy Ginzburg (Dow)Carl Willis (Kraton)Stephen Todd (Accelrys)Kim Rasmussen (LANL)Amalie Frischknecht (SNL)Andrei Gusev (ETH)Glenn Fredrickson (UCSB), Chair

Update--Leveraged ActivitiesInstitute for Collaborative Biotechnologies (ICB)

Our grant was renewed for 08-09 to support a student working in simulations of polyelectrolytes

GS – field-based PE simulations (Audus)IGERT Program of the NSF in Computational Soft Materials

The UCSB PIs participated in a proposal for graduate training that would commence Fall 2009 (Main PI: Joan Shea)

We hope to hear very soon regarding the fate of this proposalCenter for Functional Engineered Nanoscale Architectures (FENA) at UCLA (SRC & DARPA funding)

Fredrickson and Carcia-Cervera are co-PIs on a program in block copolymer lithography

GS – SCFT on curved manifolds, polymer brushes (Chantawansri)50% GS – SCFT simulations of graphoepitaxy (Hur)

Sandia National LabsWe have a new joint project with A. Frischknecht on patterning surfaces via mixed polymer brushes (Hur @ 50%)

Institute for Multiscale Materials Science (IMMS) – UCSB/LANLWe have a new joint project with Rasmussen and Welch on field-based simulations on the RoadRunner architecture, and modeling of artificial membranes (Chen @ 50%)

Leveraged Activities – Ctd.Materials Research Laboratory (NSF MRSEC)

Several of the PIs participate in MRL programs and have access to MRL computational facilities. The MRL was renewed for 2006-2012 at $20.5MThe MRL computing facility is continuing to upgrade towards a goal of 128+ serial and 128+ parallel processors

The Problem—Design of Polymer Formulations

Polymer formulations are complex fluids:

Multiphase plasticsSolution formulationsProcessed foods…Can exhibit complex self-assembly and phase behavior

Relationship between formulation, structure, rheologyand properties difficult to establish

Trial and error experimentation is norm

We aim to develop theoretical methods and software tools that can aid and accelerate experimental designs

Scales and Approaches to Fluids Simulation

Sub-atomic< 1Å

Fields(wavefunctions, density functionals)

Ab initio quantum chemistry, electronic structure

Atomic to mesoscopic1Å -- 1µm

Particles(positions, momenta)

Classical MD, MC, BD

Continuum> 1µm

Fields(densities, velocities, stresses)

PDEs of mass, momentum, energy flow, elasticity

We are computing with fields in the atomic-mesoscopic regime!

Scale MethodDOF

Why Field-Based Simulations of Polymer Fluids?

Relevant spatial and time scales cannot be accessed by atomistic “particle-based” simulationsUse of fluctuating fields, rather than particle coordinates, has potential computational advantages:

Simulations become easier at high density & high MWMore seamless connection to continuum mechanics Systematic coarse-graining by numerical RG appears feasible

Copolymer nanocomposite BJ Kim `06

Microemulsion, Bates ‘97

Mean-Field Approximation: SCFT

• SCFT is derived by a saddle point approximation to the field theory:

• The approximation is asymptotic for

• We can simulate a field theory at two levels:

• “Mean-field” approximation (SCFT): F ≈ H[w*]

• Full stochastic sampling of the complex field theory: “Field-theoretic simulations” (FTS)

High-Resolution SCFT

By the above methods we can compute saddle points using ~107 or more plane waves

Unit cell calculations for high accuracy with variable cell shape to relax stress

Initial condition has desired symmetry

Large cell calculations for exploring self-assembly in new systems

Initial condition is randomComplex geometries can be addressed with a maskingtechnique

A. Bosse

S. Sides, K. Katsov

T. Chantawansri SPHEREPACK

Block Copolymer Lithography“Unnatural” BC Morphologies

Nealey et al., Science, 2008, 321, 936 Ross et al., Science, 2008, 321, 939IBM Airgap Technique

Coating Ordering Development

22

Tetragonal Ordering by Square Confinement

In bulk, AB block copolymers pack cylinders or monolayers of spheres in hexagonal latticesTetragonal (square) lattices are preferred for memory and other devices and conform to circuit design standardsSCFT simulations suggest we can use graphoepitaxy in square wells to force tetragonal orderLimitations:

Need to change polymer: e.g. add majority block A homopolymer to AB diblock Surface/bulk competition restricts method to small lattices

Total A segment concentration

A homopolymer segment concentration

Walls promote tetragonal ordering upon annealing

Su-mi Hur

23

Line Edge Roughness Effects

Conclusion: Tetragonal order is robust, except against long-wavelength boundary perturbations of large amplitude

A. Onikoyi , E. J. Kramer (2008)

The top-down lithography used to create wells will leave rounded corners and line edge roughnessWhat will be the impact on self-assembly?

Su-mi Hur

24

New Block Copolymer Formulations

In collaboration with the Hawker and Kramer groups, we have designed new AB + B’C copolymer blends that form square lattices at equilibrium & without confinement!Current experimental design is based on a supramolecular diblock blend

Relies on H-bonding between hydroxy-styrene (hS) and 4-vinyl pyridine (4VP) to suppress macrophase separation

C. Tang, E. Lennon, G. Fredrickson, C. Hawker, E. Kramer, Science 322, 429 (2008)

Remove A Remove A & COriginal film

The supramolecular diblock system

T (1/χN)

z h/χN

1. Calculated within the SCFT (mean-field) approximation

2. Note the trend with N: re-entrance for longer chains.

NA =NB, zA=zB symmetric case

Feng, E. Lee, W., and Fredrickson, G. H., Macromolecules, 40, 693-702, 2007.

Current Activities in Supramolecular Polymer Modeling

• Richard Elliott– Is extending our models and numerical methods to telechelic functional

polymers that reversibly link to form extended chains– The next frontier will be tri- and tetra- functional systems that reversibly

link to produce inhomogeneous networks

• Zoltan Mester– Is starting a new project in partnership with DSM to develop models of

living polyester thermoplastic elastomers

“Unnatural” Block Copolymer Morphologies:poly-HIPE Structures

• In collaboration with Kraton Polymers, Nate Lynd and Folusho Oyerokunworked on the design of novel PS-PB and PS-PI “Mikto-Polymers” that maintain the PS domains discrete at very high volume fraction:

– Stronger elastomers, but with good elastic recovery– Better thermal stability

• Such block copolymers could also function as ideal “AB” surfactants in blends with A and B homopolymers to stabilize poly-HIPE structures!

B

S

SS

In conventional SBS triblock copolymers, the PS domains are only discrete (discontinuous) for fS < 0.3

SCFT Phase Diagram (n=3 arms)χN =40

Block length asymmetry:

Optimal design:

τ ≈ 0.9, PS phase discrete at fS > 0.6!!

Faceted Domains, like HIPE!!

τ = 0.9, fS = 0.66, n=5

N. Lynd, F. Oyerokun

Kraton Polymers

Block Copolymer Morphology Change Induced by Nanoparticles

By adding PS coated nanoparticles

Hybrid Particle/Field Simulations PS-b-P2VP 58k-57k/ Au-PSLow particle conc. Low particle conc.

High particle conc. High particle conc.

Lamellar

HexagonalBJ Kim, SW Sides, EJ Kramer, GH Fredrickson, PRL 96, 250601 (2006)

Simpler Route to “Nanoparticle Surfactants”

Decrease coverage Σon Au surface

AuAu

• Controlling nanoparticle location simply by varying single coverage parameter (Σ)

• Exploit the favorable interaction between Au surface and one of the matrix polymers (P2VP)

PSP2VP PS

P2VP

B. J. Kim, E. J. Kramer, C. J. Hawker, GHF

φp

Bicontinuous Structure

0.50

Macrophaseseparation

0 0.10 0.20 0.30

100 nm

Lamellar

0.40

PS-b-P2VP (Mn=91k-105k) with Au-PS (Mn=2.5k, ∑=0.85 chains/nm2)

B.J. Kim, G.H. Fredrickson, C.J. Hawker and E. J. Kramer, Langmuir, 23, 7804 (2007)

Current Efforts in Hybrid Particle-Field Simulations

• Dominik Duechs– “Janus” particles with inhomogeneous

surface interactions– Particles of arbitrary shape

• Tanya Chantawansri– SCFT on the sphere – polymer-adsorbed

and polymer-tethered particles

• Scott Sides (Tech-X)– We are going to extend our capabilities in

this area in collaboration with Scott

“A”

“B”

Polyelectrolyte Complexation: Complex Coacervates

Aqueous mixtures of polyanions and polycations complex to form dense liquid aggregatesFluctuation-dominated: SCFT fails!Applications include:

Food/drug encapsulationDrug/gene delivery vehiclesPurification/separationsBio-inspired adhesives

Cooper et al (2005) Curr Opin Coll. & Interf. Sci.10, 52-78.

H. Waite (UCSB) “Sandcastle worms”

+ + +

--

-

Ongoing Activities in Polyelectrolyte Modeling

• Debra Audus– Asymmetric coacervate models– analytical one loop– Validation of Duechs code– Validation of models in context of Tirrell group experiments

• Rajeev Kumar– Rigidity effects in polyelectrolyte complexation– Models and computational approaches for zwitterionic polymers

Advances in Field-based Simulation Methodology

• Free energy evaluation methods– Erin Lennon developed a thermodynamic integration scheme that can be coupled

with complex Langevin sampling to compute absolute or relative free energies of homogeneous or inhomogeneous fluid phases

– We plan to collaborate with Prof. Scott Shell to explore alternative approaches, such as flat histogram techniques

• Gibbs Ensemble simulation methods– Rob Riggleman is developing the capability to conduct field-based simulations in

the “Gibbs Ensemble”, which allows for direct simulation and observation of phase coexistence

• Coarse-graining/renormalization group methods– Mike Villet is developing methods by which simulations of field theories on a fine

lattice can be used to parameterize field theory models on a coarse lattice. This will allow simulations to be conducted on much larger systems than presently possible

• Numerical methods for polymer brushes– Tanya Chantawansri and Su-mi Hur have developed efficient numerical methods

for conducting high resolution SCFT and FTS studies of end-tethered polymers. This should have broad implications for problems in colloid and nanoparticle science, as well as nanopatterning of surfaces

Software statusWe have consolidated our software in one modular C++ code (Cochran code) and have implemented a CVS server for version control, bug fixesCurrent capabilities

SCFT for arbitrary tree-like branched architectures, solvents, blends, copolymers in canonical and GC ensemblesFTS of binary species modelsStationary and mobile spherical nanoparticlesFilms and complex geometries by maskingDiffusive dynamics for SCFTStress distributions

Future capabilitiesFTS for arbitrary models, including polyelectrolytes and ionsSupramolecular polymers and networksPolydispersityQuasi-static stress-strain properties Other ensembles, e.g. NPTThin film module with boundary conditions/Chebyshev basedGrafted polymer layersMobile non-spherical inclusionsGibbs ensemble simulationsCoarse-graining and multiscale techniquesRealistic dynamics including hydrodynamics, processing behavior

Licensing to Accelyrs

UCSB and Accelyrs completed an agreement to provide Accelyrs an exclusive license to market and sell our CFDC code (Cochran C++ code) as part of its Materials Studio product: MesotekCFDC members of good standing will continue to receive royalty-free software distributions from the centerMembers can also directly purchase the Accelyrs product, if they desire the improved user interface and integrated features of Materials StudioWe expect that the partnership will help us to professionally manage our software assets

CFDC Annual Meeting Agenda – 2/2/2009 – Morning Session

9:00-9:30 Welcome and Update (Glenn Fredrickson, Director, CFDC)9:30-10:00 Two Modes of Energy Dissipation in Heterogeneous Polymeric Materials with Lossy Interfaces (Andrei Gusev, ETH)10:00-10:30 Coffee Break10:30-11:00 Mesotek – Perspectives and Future Directions (Eric Cochran, Iowa State U.)11:00-11:30 Design of Thermoplastic Elastomers: Radial (ABA)n and A(BA)n Miktoarm Architectures (Nate Lynd, UCSB)11:30-12:00 Supratelechelics: Thermoreversible Bonding in Difunctional Polymer Blends (Richard Elliott, UCSB)12:00-1:00 Lunch – 3rd Floor MRL patio

CFDC Annual Meeting Agenda – 2/2/09 – Afternoon Session

1:00-1:30 Phase Behavior in Nanoparticle/Polymer Thin Films from Fluids Density Functional Theory (Amalie Frischknecht, Sandia National Labs)1:30-2:00 Systematic Coarse-Graining of Fluid Field Theories (Mike Villet, UCSB)2:00-2:30 Numerical Methods for Polymer Brushes Using Self-Consistent Field Theory(Tanya Chantawansri, UCSB)2:30-2:45 Molecular Dynamics Simulation of Entangled Polymer Melts Based on the Continuous Chain Model (Aruna Mohan, UCSB)2:45-3:15 Coffee Break3:15-3:45 Simulations of Reversible Polymer Networks (Rob Hoy, UCSB)3:45-4:15 Study of Block Copolymer Lithography Using SCFT (Su-mi Hur, UCSB)4:15-4:30 Conformational Characteristics of a Single Polyzwitterionic Chain: Effect of Salt (Rajeev Kumar, UCSB)4:30-5:00 Field-Theoretic Simulations of Complex Coacervates (Debra Audus, UCSB)5:00-5:15 Mean Field Model of Self-Assembling Lipid Membranes with Embedded Proteins (Kang Chen, UCSB)5:15 Wrap-up, close CFDC meeting5:15-6:00 CFDC Steering Committee Meeting (Members Only, Rm 3117D MRL)

CFDC Dinner – 7pm Flavor of India —sign up at break