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  • PPARTICLEARTICLE--STABILIZEDSTABILIZED FOAMSFOAMS ANDAND THEIRTHEIR POTENTIALPOTENTIAL APPLICATIONSAPPLICATIONS

    Urs T. Gonzenbach Dr. Sc. ETH

    Nonmetallic Inorganic Materials, Department of Materials, ETH Zü i h S it l dETH Zürich, Switzerland

  • 22

  • 33

  • 4 AAPPLICATIONSPPLICATIONS OFOF POROUSPOROUS CERAMICSCERAMICS

    4

    • thermal and corrosion resistance

    Advantages

    • thermal and corrosion resistance • low density • low thermal conductivityy • controlled permeability • high surface area • …

    Applications

    • high-temperature thermal insulation • filters for molten metals exhaust gases

    pp

    • filters for molten metals, exhaust gases • catalyst carriers • bone graftsbone grafts • lightweight materials • …

  • 5 DDIRECTIRECT FOAMINGFOAMING

    5

    but

    excessive coarsening in the wet state due to

    • Ostwald ripening (difference in Laplace pressures)Ostwald ripening (difference in Laplace pressures) • drainage • coalescence of single bubbles

  • 6 CCOARSENINGOARSENING OFOF SURFACTANTSURFACTANT--STABILIZEDSTABILIZED FOAMSFOAMS

    6

    ∆t = 4h

    How can the foam stability be improved?How can the foam stability be improved?

  • 7 PPICKERINGICKERING EMULSIONSEMULSIONS

    7 W. Ramsden. “Separation of solids in the surface-layers of solutions and 'Suspensions'. Preliminary Account.”, Proceedings of the Royal Society, 72[479], 156-164,1903. S. U. Pickering. “Emulsions”, Journal of the Chemical Society, 91, 2001-2021,1907.

    http://royalsociety.org

    any fine particles are able to stabilize oil-in-water emulsions

    Percival Spencer Umfreville Pickering

    emulsions enhanced stability compared to surfactant- stabilized emulsionsp g

    (1858 – 1920)

  • 8 SSTABILIZATIONTABILIZATION OFOF THETHE AIRAIR--WATERWATER INTERFACEINTERFACE

    8

    Free energy gain by loosing an area of fluid-gas interface

    long-chain surfactants

    area of fluid gas interface

    particles

    i l b f i b hi hili ( j i l )particles can be surface active, but are not amphiphilic (expect janus particles) particles strongly held at interface, enhanced stability of the foam

  • 9 PPARTICLESARTICLES ININ MIXTURESMIXTURES OFOF IMMISCIBLEIMMISCIBLE PHASESPHASES

    9

    Oxides: Polymers:condition to obtain Al2O3, ZrO2, SiO2, Ca3(PO4)2, hydroxyapatite,

    Polyethylene (PE), Polyvinyldifluoride , Teflon (PTFE),

    FOAMS or

    MISTS or

    … …O/W EMULSIONS W/O EMULSIONS

  • 10 IINN--SITUSITU HYDROPHOBIZATIONHYDROPHOBIZATION OFOF PARTICLESPARTICLES

    10

    short-chain amphiphilic molecules as surface modifiers

    → high solubility in water → high concentration of modified particles → stabilization of large interfacial area

    Gonzenbach et al. Angewandte Chemie-International Edition, 2006.

    → stabilization of large interfacial area

  • 1111

    TTHEHE FOAMINGFOAMING PROCESSPROCESS

  • 12 SSTABILITYTABILITY OFOF THETHE WETWET FOAMSFOAMS

    12

    Gillette razor foam

    our foams

    100μm100μm100μm100μm

    Suspension homogeneously foamed throughout the whole volume Improved wet foam stability compared to state-of-the-art foams

    Gonzenbach et al., Journal of the American Ceramic Society, 2007.

  • 5µm

    50µm

  • FFOAMOAM PROCESSINGPROCESSING

    1 21 2

    suspension foaming preparation

    g

    3 4

    drying sintering

  • 1515

    3cm

  • 1616

    100µm

  • 1717

    100µm

  • 18 PPROPERTIESROPERTIES OFOF POROUSPOROUS ALUMINAALUMINA

    18

  • 1919

    1µm

  • 20 VVERSATILITYERSATILITY OFOF THETHE METHODMETHOD

    20

    Method can be applied to many different materials, e.g.

    Ceramics • Al2O3 • SiO

    Metals • Ti

    • Al

    Polymers • PVDF

    • PTFE• SiO2 • ZrO2 • Ca3PO4

    • Al

    • Ni/Ti

    • ...

    • PTFE

    • PE

    • PPCa3PO4 • Cements

    • ...

    ... PP

    • ...

    1cm 1cm 1cm

  • CCAPSULEAPSULE PROCESSINGPROCESSING

    1 21 2

    suspension foaming preparation

    g

    3 4

    dilution filtration

  • 2222

    20µm

  • 2323

    2µm

  • 2424

    5µm10µm

  • 25 PPOTENTIALOTENTIAL APPLICATIONSAPPLICATIONS

    25

    PPPPLATFORMLATFORM TTECHNOLOGYECHNOLOGYTTECHNOLOGYECHNOLOGY

  • 26 FFOAMSOAMS ANDAND EMULSIONSEMULSIONS ATAT ETHZETHZ

    26

    Ceramic foams Metallic foams Polymeric foams

    Ludwig J. Gauckler Jörg F. Löffler Paolo Ermanni

    Urs T. Florian StephanElena David Megias- Mario Gonzenbach Dalla Torre

    p BusatoTervoort

    g Alguacil Mücklich

    Laboratory of Metal Center of Structure Franziska

    Krauss Adrienne Nelson Joanna WongIlke

    Akartuna Philip N.

    Sturzenegger Ben

    Seeber Nonmetallic Inorganic Materials

    Laboratory of Metal Physics and Technology

    Center of Structure Technology

    KraussAkartuna Sturzenegger Seeber

  • 27 AcknowledgmentsAcknowledgments

    27

    Prof. Dr. Ludwig J. Gauckler, Dr. André R. Studart, Dr. Elena Tervoort

    Ilke Akartuna Franziska Krauss Philip Sturzenegger Mario Mücklich

    Ambrosini, Jan

    Ilke Akartuna, Franziska Krauss, Philip Sturzenegger, Mario Mücklich

    Kümin, Cyrill

    Bardill, Anita

    Bihl, Andreas

    Nägeli, Rahel

    Seeber, Benedikt

    Bonderer, Lorenz

    Dietiker, Marianne

    Siegfried, Michael

    Steinlin, David

    Elser, Pierre

    Geiser, Valérie

    I k B i

    Strehler, Claudia

    Sturzenegger, Philip

    Wi ä hti A dIwanowsky, Boris

    Kontic, Roman

    Wiprächtiger, Andreas

    Funding: ETH Zürich, CIBA, Holcim, CCMX, SPERU

  • 28ThankThank oo !!ThankThank oo !! 28ThankThank youyou!!ThankThank youyou!!

    1cm