Water‐based freeze casting: Adjusting hydrophobic polymethylsiloxane for obtaining hierarchically ordered porous SiOC

The hydrophobic properties of methyl poly siloxane (MK) were pushed into the “hydrophilic” range by cross‐linking it with (3‐aminopropyl)triethoxysilane (APTES) and subsequent pyrolysis to enable water‐based freeze casting. Filler properties are investigated by varying the ratios of MK to APTES (1:1...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 2017-05, Vol.100 (5), p.1907-1918
Main Authors: Zhang, Huixing, Fidelis, Clara Lana, Serva, Ana Luiza Teixeira, Wilhelm, Michaela, Rezwan, Kurosch
Format: Article
Language:English
Subjects:
Aminopropyltriethoxysilane
Crosslinking
Fillers
freeze casting
Hydrophobicity
Lamellar structure
micro/meso/macropore
polymer derived ceramics
Pyrolysis
silicon oxycarbide
Siloxanes
surface characteristics
Zeta potential
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Summary:The hydrophobic properties of methyl poly siloxane (MK) were pushed into the “hydrophilic” range by cross‐linking it with (3‐aminopropyl)triethoxysilane (APTES) and subsequent pyrolysis to enable water‐based freeze casting. Filler properties are investigated by varying the ratios of MK to APTES (1:1, 1:2, 1:3, 1:4, 1:5), and pyrolysis temperatures (400°C, 500°C, 600°C) for the purpose of determining an optimal set of characteristics for freeze casting. Additionally, filler selection for this purpose is facilitated by analysis of zeta potential values and vapor adsorption. It was found that water‐based freeze casting with hybrid fillers, followed by a pyrolysis step (600°C‐700°C), leads to a SiOC ceramic monolith with a lamellar pore morphology and a hierarchically ordered micro/meso/macropore structure. Samples pyrolyzed at 1000°C contain mesopores, having a SSA as high as 51.6 m2/g. The hierarchically porous structure is very promising for applications involving gas or liquid transportation.
ISSN:0002-7820
1551-2916
DOI:10.1111/jace.14782