Regularities of Sol-Gel Processes in the Preparation of Polysilicates

Resumo

The regularities of sol-gel processes in the preparation of potassium polysilicate based on silica hydrosol (Ludox AS-40) are studied. The potassium hydroxide–silica molar ratio (silicate modulus M = [SiO₂]/[Me₂O]) is set by introducing potassium hydroxide into the sol. The addition of alkali at the initial stage induces sol coagulation. The mechanism of alkali effect is considered taking into account the reactivity of silica (the polycondensation and depolymerization reactions) and the aggregative stability of the colloidal system.