Synthesis of silica aerogels from waterglass via new modified ambient drying

A new modified ambient drying process for synthesizing silica aerogels cost-effectively from waterglass has been developed. Crack-free silica aerogels were obtained via solvent exchange/surface modification of wet gels using IPA/TMCS/n-Hexane solution. Silica aerogels were heated at different temperatures. The effects of heating temperature on chemical bonding state of aerogels were investigated by means of DTA and FTIR. The surface characteristic of the aerogel was hydrophobic when heat-treated under 350degreesC. The porosities, densities, and specific surface areas of the silica aerogels were in the range of 93-94%, 0.12-0.15 g/cm(3), and similar to630 m(2)/g, respectively. Distinct spring back phenomena were observed in surface modified wet gels during drying. (C) 2002 Kluwer Academic Publishers.