Silica nanoparticles obtained by microwave assisted sol-gel process: multivariate analysis of the size and conversion dependence

Silica nanoparticles were synthesized by the sol-gel method in alcoholic solution under microwave irradiation in the presence of an ammonium catalyst. The effect of the reaction time, the reaction temperature, water and ammonium concentrations on particle size and conversion (measured by light scattering and FTIR respectively) were analyzed using multivariate analysis. The results showed that water and ammonium concentrations are the main factors that control the particle size and the conversion. Both properties increase with water and ammonium concentration. Moreover, comparing with the results obtained using traditional heating, the microwave heating gave rise to higher reaction rate and narrower dispersion of the particle size.