Preparation of monodisperse silica particles in emulsion media

The main aim of this work was to prepare monodisperse silica particles with specific properties suitable for chromatographic adsorbents. Silica particles were obtained in W/O emulsions by reaction of tetraethyl orthosilicate, using either NH3 or HCl as catalysts. Emulsions were prepared by physicochemical, low energy emulsification methods. Monodisperse particles were obtained by using an appropriate emulsification method and by controlling emulsion stability during reaction. Silica particles, with mean sizes from 2 μm to 1000 μm, were prepared using HCl as a catalyst while NH3 produced particles with mean sizes from 0.5 μm to 10 μm. The size was controlled by the mixing ratio between two different type of surfactants. Silica particles were characterised by optical and electron microscopy, nitrogen sorption, FTIR, small angle X-ray scattering and thin layer chromatography. The results showed that monodisperse spherical particles with a high specific surface, appropriate for chromatographic purposes, can be prepared in emulsion media using HCl as a catalyst.