Sol-gel synthesis, porous structure, and mechanical property of polymethylsilsesquioxane aerogels

抄録

Organic-inorganic hybrid aerogels with polymethylsilsesquioxane (PMSQ, CH₃SiO_1.5) composition have been synthesized by a modified two-step sol-gel process. The precursor alkoxysilane is hydrolyzed in a weakly acidic condition, and subsequently allowed to undergo polycondensation in a weakly basic condition which is brought up by the hydrolysis of urea. Two kinds of surfactant (nonionic and cationic) have been utilized to suppress macroscopic phase separation. The resultant porous morphology could be modified by the kind of surfactant used. Small angle X-ray scattering (SAXS) and nitrogen adsorption have been employed to assess the porous morphology and it is found that the obtained PMSQ aerogels consist of aggregated particles and each particle contains micropores. Compressive mechanical properties have also been discussed based on the obtained information on porous morphology.