Tailoring a Thermally Stable Amorphous SiOC Structure for the Separation of Large Molecules: The Effect of Calcination Temperature on SiOC Structures and Gas Permeation Properties.

A SiOC membrane with high oxidative stability for gas separation was tailored by utilizing vinyltrimethoxysilane, triethoxysilane, and 1,1,3,3-tetramethyldisiloxane as Si precursors. Amorphous SiOC networks were formed via the condensation of Si-OH groups, the hydrosilylation of Si-H and Si-CH=CH groups, and a crosslinking reaction of Si-CH groups, respectively. The crosslinking of Si-CH groups at temperatures ranging from 600 to 700 °C under a N atmosphere was quite effective in constructing a Si-CH-Si unit without the formation of mesopores, which was confirmed by the results of N adsorption and by the gas permeation properties.