Preparation of monodispersed silica sol with small particle size, narrow size distribution, and high conversion

Abstract

Monodispersed silica sol with a small particle size, narrow size distribution, and high conversion was prepared via a modified Stober method, and an orthogonal test method was used to investigate the influence of TEOS concentration, R (H2O/TEOS), ammonia concentration, and reaction temperature on the particle size, size distribution, and conversion of silica sol. It was found that the remarkable factors affecting the particle size from a large to a small order were ammonia concentration, reaction, temperature, and R (H2O/TEOS) value; similarly, the remarkable factors affecting the silica sol conversion from a large to a small order were the R (H2O/TEOS) value and reaction temperature in decreasing order of influence. None of the factors investigated in this study exhibited a significant effect on the particle size distribution. The optimal synthesis conditions for the preparation of monodispersed silica sol with small particle size and high conversion were as follows: TEOS concentration = 0.4 mol/L; R (H2O/TEOS) = 60; ammonia concentration = 0.10 mol/L; reaction temperature = 75 °C. The average particle size of monodispersed silica sol under optimum conditions was 5.25 ± 0.77 nm, and the conversion was 94.05%. Besides, this study also provides a systematic experimental and theoretical basis for the preparation of different particle sizes monodispersed silica sol with high conversion.