Directionally aligned macroporous SiOC via freeze casting of preceramic polymers

Naviroj, Maninpat; Miller, Steve; Colombo, Paolo; Faber, K. T.

doi:10.1016/j.jeurceramsoc.2015.02.013

Cited by 108 publications

(69 citation statements)

References 34 publications

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“…Organic precursors, such as polycarbosilane were mixed with camphene to get a homogenous polymer solution; the pores formed by thermally induced phase separation during freezing . Poly(methyl‐silsesquioxane) has also been used with tert‐butyl alcohol, camphene, and cyclohexane to get SiOC porous material; precise control of cross‐linking is required to prevent early gelation or poor mechanical integrity . Polymer‐derived ceramics have the advantages of adjusting pore sizes at different scales and altering surface characteristics via processing parameters, while freeze casting can be used to adjust the pore structure and permeability of the macroprous monolith.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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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.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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“…serves as a template to be sublimed, resulting in a dendritic, aligned channeled matrix710. Although rare, preceramic polymers have also been investigated in the production of aligned porosity ceramics by freeze casting61112. In the unidirectional solidification process, generally a molten metal is pressurized in a gas atmosphere (e.g.…”

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confidence: 99%

Gradient-Hierarchic-Aligned Porosity SiOC Ceramics

Vakifahmetoğlu

Zeydanlı

Innocentini

et al. 2017

Sci Rep

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This work describes a simple technique to produce porous ceramics with aligned porosity having very high permeability and specific surface area. SiOC-based compositions were processed from blends of three types of preceramic polymer and a catalyst, followed by curing and pyrolysis. The heating applied from the bottom of molds promoted the nucleation, expansion and rising of gas bubbles, and the creation of a ceramic matrix with axially oriented channels interconnected by small round pores. The samples were analyzed by SEM, tomography, BET, water immersion porosimetry and permeation to gas flow. The resulting bodies presented levels of open porosity (69.9–83.4%), average channel diameter (0.59–1.25 mm) and permeability (0.56–3.83 × 10−9 m2) comparable to those of ceramic foams and honeycomb monoliths, but with specific surface area (4.8–121.9 m2/g) typical adsorbents, enabling these lotus-type ceramics to be advantageously used as catalytic supports and adsorption components in several environmental control applications.

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“…Porous alumina was the first porous ceramic to be templated using freeze casting . To date, this technique has been applied to naturally occurring minerals, binary oxides or their composite, such as hydroxyapatite, silica, and zirconia, to obtain solids with controlled porosity for application in bone regeneration, filtration media, catalyst support, or thermal insulation . The technique has also been applied to the preparation of bilayer thin films for solid oxide fuel cells, which highlights its versatility.…”

Section: Introductionmentioning

confidence: 99%

“…The technique has also been applied to the preparation of bilayer thin films for solid oxide fuel cells, which highlights its versatility. While the most common solvent or dispersion medium used for freeze casting is water, solvents such as camphene, tert‐butyl alcohol, cycloalkanes, dioxane, or dimethyl carbonate have also been employed, providing alternatives to water for moisture‐sensitive ceramics, as is the case for most Li‐ion solid electrolytes …”

Section: Introductionmentioning

confidence: 99%

Dense freeze‐cast Li₇La₃Zr₂O₁₂ solid electrolytes with oriented open porosity and contiguous ceramic scaffold

et al. 2018

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Freeze casting is used for the first time to prepare solid electrolyte scaffolds with oriented porosity and dense ceramic walls made of Li 7 La 3 Zr 2 O 12 (LLZO), one of the most promising candidates for solid state battery electrolytes. Processing parameters -such as solvent solidification rate, solvent type, and ceramic particle size -are investigated, focusing on their influence on porosity and ceramic wall density. Dendrite-like porosity is obtained when using cyclohexane and dioxane as solvents. Lamellar porosity is observed in aqueous slurries resulting in a structure with the highest apparent porosity and densest ceramic scaffold but weakest mechanical properties due to the lack of interlamellar support. The use of smaller LLZO particle size in the slurries resulted in lower porosity and denser ceramic walls. The intrinsic ionic conductivity of the oriented LLZ ceramic scaffold is unaffected by the freeze casting technique, providing a promising ceramic scaffold for polymer infill in view of designing new types of ceramic-polymer composites.

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Directionally aligned macroporous SiOC via freeze casting of preceramic polymers

Cited by 108 publications

References 34 publications

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

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

Gradient-Hierarchic-Aligned Porosity SiOC Ceramics

Dense freeze‐cast Li₇La₃Zr₂O₁₂ solid electrolytes with oriented open porosity and contiguous ceramic scaffold

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Directionally aligned macroporous SiOC via freeze casting of preceramic polymers

Cited by 108 publications

References 34 publications

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

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

Gradient-Hierarchic-Aligned Porosity SiOC Ceramics

Dense freeze‐cast Li7La3Zr2O12 solid electrolytes with oriented open porosity and contiguous ceramic scaffold

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Product

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Dense freeze‐cast Li₇La₃Zr₂O₁₂ solid electrolytes with oriented open porosity and contiguous ceramic scaffold