1990 Volume 98 Issue 1139 Pages 647-652
The structure and distribution of hydrolysis and polycondensation products of methyltriethoxysilane present in aqueous solutions containing sodium ions have been investigated with the trimethylsilylation technique and by 29Si n. m. r. spectroscopy. It has been found that the polymerization of hydrolysis products of methyltriethoxysilane in aqueous solutions containing sodium ions takes place randomly and a variety of the species with different structures is present. However, the degree of polycondensation of the species in the aqueous solutions at a certain Si concentration is much lower than that of silicate species, which may be attributed to the difference in the functionality of silane in the species formed from methyltriethoxysilane and silicate anions or the repulsion between methyl groups in the species from methyltriethoxysilane. In addition, 29Si n. m. r. peaks due to the monomeric, dimeric, and linear and cyclic trimeric species consisting only of the CH3SiO33- unit have been assigned.