Characterization of hydrophobic SiO2 powders prepared by surface modification on wet gel

Hydrophobic porous silica has been prepared by surface modification of TEOS (tetraethylorthosilicate) wet gel with 6 and 12 vol.% of TMCS (trimethylch lorosilane). We characterized the products by using FT-IR, TGA, DTA, N-2 ad sorption/desorption, contact angle and SEM. Surface silanol groups of the g el were widely replaced by-Si(CH3)(3) to result in a hydrophobic SiO2 powde r as confirmed by contact angle measurements with H2O, 1-butanol and ethano l. The modified dried gels had a surface area of 950-1000 m(2)/g (average p ore size 120 Angstrom), compared to the non-modified surface which had a su rface area of 690 m(2)/g (average pore size 36 Angstrom). The adsorption/de sorption isotherm curves indicated they had similar pore characteristics as aerogels prepared by the supercritical drying process.