Dependence of SiO2> Gel Structure on Gelation Conditions and Sol Reaction Temperature as Followed by FTIR and Nitrogen Adsorption Measurements

The acid catalyzed hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in the absence of alcohol was studied using cylindrical internal reflectance Fourier transform infrared (CIR-FTIR) spectroscopy at four temperatures. Special attention was given to the low-frequency band around 940 cm-1 and its evolution corresponding to the changing silicic acid concentration. This method compared well with other published methods for studying condensation kinetics.