Post on 21-May-2020
PPARTICLEARTICLE--STABILIZEDSTABILIZED FOAMSFOAMS ANDAND THEIRTHEIR
POTENTIALPOTENTIAL APPLICATIONSAPPLICATIONS
Urs T. GonzenbachDr. Sc. ETH
Nonmetallic Inorganic Materials, Department of Materials,ETH Zü i h S it l dETH Zürich, Switzerland
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33
4AAPPLICATIONSPPLICATIONS 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• …
5DDIRECTIRECT 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
6CCOARSENINGOARSENING OFOF SURFACTANTSURFACTANT--STABILIZEDSTABILIZED FOAMSFOAMS
6
∆t = 4h
How can the foam stability be improved?How can the foam stability be improved?
7PPICKERINGICKERING EMULSIONSEMULSIONS
7W. 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
emulsionsenhanced stability compared to surfactant-stabilized emulsionsp g
(1858 – 1920)
8SSTABILIZATIONTABILIZATION 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
9PPARTICLESARTICLES ININ MIXTURESMIXTURES OFOF IMMISCIBLEIMMISCIBLE PHASESPHASES
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Oxides: Polymers:condition to obtainAl2O3, ZrO2, SiO2, Ca3(PO4)2,hydroxyapatite,
Polyethylene (PE),Polyvinyldifluoride ,Teflon (PTFE),
FOAMSor
MISTSor
… …O/W EMULSIONS W/O EMULSIONS
10IINN--SITUSITU HYDROPHOBIZATIONHYDROPHOBIZATION OFOF PARTICLESPARTICLES
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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 FOAMINGFOAMINGPROCESSPROCESS
12SSTABILITYTABILITY OFOF THETHE WETWET FOAMSFOAMS
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Gillette razor foam
our foams
100μm100μm100μm100μm
Suspension homogeneously foamed throughout the whole volumeImproved 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 foamingpreparation
g
3 4
drying sintering
1515
3cm
1616
100µm
1717
100µm
18PPROPERTIESROPERTIES OFOF POROUSPOROUS ALUMINAALUMINA
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1919
1µm
20VVERSATILITYERSATILITY OFOF THETHE METHODMETHOD
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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 foamingpreparation
g
3 4
dilution filtration
2222
20µm
2323
2µm
2424
5µm10µm
25PPOTENTIALOTENTIAL APPLICATIONSAPPLICATIONS
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PPPPLATFORMLATFORMTTECHNOLOGYECHNOLOGYTTECHNOLOGYECHNOLOGY
26FFOAMSOAMS ANDAND EMULSIONSEMULSIONS ATAT ETHZETHZ
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Ceramic foams Metallic foams Polymeric foams
Ludwig J. Gauckler Jörg F. Löffler Paolo Ermanni
Urs T. Florian StephanElena David Megias- MarioGonzenbach Dalla Torre
pBusatoTervoort
gAlguacil Mücklich
Laboratory of Metal Center of StructureFranziska
KraussAdrienne Nelson Joanna WongIlke
AkartunaPhilip N.
SturzeneggerBen
SeeberNonmetallic Inorganic Materials
Laboratory of Metal Physics and Technology
Center of Structure Technology
KraussAkartuna Sturzenegger Seeber
27AcknowledgmentsAcknowledgments
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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