Hydrolysis and polycondensation of ethyl silicates. 3. Hydrolysis and polycondensation of ETS40 (ethyl silicate 40) in the presence of water colloidal silica sols

Abstract The hydrolysis and condensation of ETS40 (ethyl silicate 40) in the presence of water colloidal silica sols were studied with the aid of gas chromatography, potentiometry and gelation tests. The acids HCl, H 2 SO 4 , HNO 3 , HCOOH, (COOH) 2 and p -toluenesulfonic acid were used as catalysts. Water—ethanol solutions of the reaction products of the hydrolysis and condensation of ETS40 in the presence of water colloidal silica sols were stable for more than 2 years. This stability was caused by a low water content in the water—ethanol solutions of the reaction products, a stable pH of about 2.0 and by bonded or non-bonded interactions between ETS40 hydrolysates (ethoxyhydroxysiloxanes) and large particles of water colloidal silica sols.