A modified Stober process for the production of mesoporous Sub 2 micron silica microspheres; applications in HPLC

Mesoporous silica microspheres in the 1-2 mu m range with good size monodispersivity were synthesized by ammonia catalysed hydrolysis and condensation of tetraethylorthosilicate using methanol as solvent and cetyltrimethylammonium bromide as surfactant porogen. The mesopore diameter was subsequently expanded from < 20 to similar to 200 by a postsynthesis hydrothermal treatment in a water-amine emulsion system followed by controlled dissolution in aqueous alkali. XRD, TEM, and N(2) sorption measurements were used to characterize pore properties. Particle size measurements in conjunction with SEM were used to establish morphology and size distribution. Preliminary chromatographic results are presented which demonstrate the applicability of these particles in High Performance Liquid Chromatography (HPLC). The particle size, porosity and chromatographic performance of the particles are compared to commercial HPLC silicas.