Studies of the Initial Steps in Sol-Gel Processing of Si(OR) Sub 4 : Sup 29 Si NMR of Alkoxysilane and Alkoxysiloxane Solutions

摘要

Silicon-29 NMR has been used to investigate the initial steps of hydrolysis and condensation of tetramethoxysilane (TMOS), hexamethoxydisiloxane, and octamethoxytrisiloxane in both basic and acidic methanol solutions. Comparisons of the spectra obtained from the various starting solutions and literature reports of mono-, di-, and tri-silicic acids in aqueous solution were used to identify and assign chemical shifts to condensation intermediates in the TMOS system. The observation of cyclic intermediates in the acid catalysis of TMOS in methanol and the chemical shifts of several products of its hydrolysis and condensation are reported. 12 refs., 3 figs., 2 tabs. (ERA citation 11:041189)