PREPARATION OF MONODISPERSE COMPOSITE-PAR TICLES BY HYDROLYSIS OF METAL ALKOXIDES WITH SEED PARTICLES

Silica particles of micron size were prepared by hydrolysis and conden sation of tetraethyl orthosilicate (TEOS) with silica seed particles s ynthesized by Stober's method. Monodisperse silica particles larger th an 1 mu m in diameter were found to be produced by controlling the tot al surface area of seed particles. The final particle size in this see d growth technique could be predicted if an apparent rate constant of hydrolysis was measured. The preparation of monodisperse composite par ticles of silica-titania was also attempted by the hydrolysis of titan ium tetraisopropoxide (TTIP) with silica seed particles. It was found the monodisperse composite particles of silica-titania were obtained b y continuous addition of water.