Synthesis and Size Control of Monodisperse Silica Sol Nanospheres via a Modified Stöber Method

An effective and optimized method for synthesis silica sol nanospheres by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in the presence of aqueous alcohol solution with ammonia as catalyst was described. Under this experiment condition, monodisperse and uniform-size silica sol spheres with average diameters from 38-95nm were obtained. Here, we successfully controlled the size and shape of silica sol by fine adjusting the reaction parameters such as concentration of TEOS, value of R (H2O/TEOS) and ammonia concentration. On the basis of the experiment results, it was found that sphere size declined as the concentration of TEOS decreased. Also with the increment of ammonia concentration, the diameter of silica sol decreased slightly. However, higher R (H2O/TEOS) value would lead to larger sphere size in the range of 62-95nm. The resulting silica sol was determined by Field Emission Scanning Electron Microscopy (FE-SEM) and Fourier transformed infrared (FT-IR).