Is Supercritical So Critical? The Choice of Temperature to Synthesize SiO2 Aerogels

Abstract

The structure of SiO2-based materials obtained by hydrolysis of tetraethoxysilane and subsequent drying of SiO2 lyogels at temperatures from 85 to 265°C has been analyzed in detail. It has been found that drying conditions have no marked effect on the specific surface area of SiO2, which constitutes ~1000 m2/g in all cases. Average pore size and specific pore volume monotonically increase with drying temperature, the contribution of large mesopores (>20 nm) into total material porosity rises at high drying temperature. Drying temperature has a considerable effect on the degree and character of individual SiO2 particles aggregation.