Alcoholic Solvent Effect on Silica Synthesis—NMR and DLS Investigation

The solvent effect on the synthesis of silica particles has been elucidated through the examination of hydrolysis rate and particle growth by 29Si NMR and Dynamic Light Scattering studies, respectively, in various alcoholic solvents. Kinetic data obtained from the NMR experiments indicate that the rate of hydrolysis is fastest in 1-butanol and the rates follow an unusual order of 1-butanol > methanol > ethanol > 2-propanol > 1-propanol. This order of the rates of hydrolysis is rationalized with two opposing factors, steric hindrance reducing the rate and decrease of hydrogen bonding enhancing the rate. The final particle size increases as the alcohol molecular weight increases. This might be due to decrease in polarity of the alcohols.