The base catalyzed hydrolysis and condensation reactions of dilute and concentrated TEOS (Tetraethylorthosilicate) solutions: Draft

The synthesis of submicron silica particles by the hydrolysis and condensation of dilute and concentrated solutions of tetraethylorthosiliate (TEOS) has been studied in low-molecular weight alcohols (C/sub 1/--C/sub 4/). A base (ammonia) is used to catalyze the reaction. Raman spectroscopy, gas chromatography and the molybdate method are used to establish the hydrolysis and condensation kinetics. Dynamic and classical light-scattering techniques are employed to monitor particle growth and particle number concentration kinetics, and particle size distribution. The effects of solvent and TEOS concentration on the degree of monodispersity of the particles will be discussed. Furthermore, the chemical and particle growth data will be used to test the theories of homogeneous nucleation and coagulative nucleation, which have been proposed as the mechanisms that govern the growth of submicron monodisperse silica particle by TEOS hydrolysis. 13 refs., 4 figs., 1 tab.