RELATIONS BETWEEN THE TEXTURE OF SILICA AEROGELS AND THEIR PREPARATION

The effect of the preparation conditions on the morphology (Brunauer, Emmett and Teller surface area, micro-, meso-and macroporosity, fracta l dimension) of silica aerogels is presented. Solutions of tetramethyl oxysilane (TMOS) in methanol were used for the sol-gel reactions. The parameters were volume fraction of TMOS, pH of the medium and hypercri tical drying method (methanol or CO2). Adsorption of different gases w as used for the characterization of the size and arrangement of primar y particles at the molecular scale and thermoporometry gave informatio n on the arrangement of primary particles into aggregates.