| Summary: | Applications such as filtration require not only control over the pore structure but also over properties like surface characteristics and mechanical strength. The addition of filler particles to solution based freeze casting of preceramic polymers combines the flexibilities of freeze casting and preceramic polymers. Alumina platelets, silica spheres and preceramic filler particles with different compositions were frozen in solution based freeze casting of preceramic polymers with cyclohexane as solvent. Methyl- and methyl-phenyl polysiloxanes as well as (3-aminopropyl)triethoxysilane were used as precursors and cross-linking agent, respectively. The compressive strength increases by factors of up to 1.9 (25 vol% preceramic filler) due to enhanced isotropy of the dendritic pore structure. At lower concentrations (1.7 vol%), alumina platelets are more effective in strengthening than spherical particles. In dependence on the composition of the preceramic filler, BET surface area and the ratio of vapor uptake between water and heptane change by factors of up to 1.19 and 16, respectively. Calculations according to a linear rule of mixture fit very well with the experimental data. In summary, the versatile approach to add differing filler particles to solution based freeze casting allows for tailoring the pore structure as well as surface characteristics of macroporous monolithic samples. Keywords: Freeze-casting, Polysiloxanes, SiOC, Compressive strength, Filler particles, Porous monoliths
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