Kinetics of the early stages of the Sol-Gel process: II. Distribution of silica over molecular species

Abstract

The ratio between strongly and weakly structured species of silica at the early stages of hydrolysis and polycondensation of silicon alkoxides is investigated. It is demonstrated that this problem can be solved using the molybdate method. The kinetics of the process in water-alcohol solutions of tetraethoxysilane and tetramethoxysilane is studied as a function of the pH value of the medium and the tetraalkoxysilane : H 2 O ratio.