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 (trimethylchlorosilane). We characterized the products by using FT-IR, TGA, DTA, N-2 adsorption/desorption, contact angle and SEM. Surface silanol groups of the gel were widely replaced by-Si(CH3)(3) to result in a hydrophobic SiO2 powder as confirmed by contact angle measurements with H2O, 1-butanol and ethanol. The modified dried gels had a surface area of 950-1000 m(2)/g (average pore size 120 Angstrom), compared to the non-modified surface which had a surface area of 690 m(2)/g (average pore size 36 Angstrom). The adsorption/desorption isotherm curves indicated they had similar pore characteristics as aerogels prepared by the supercritical drying process.