Synthesis of sub-200 nm silsesquioxane particles using a modified Stöber sol-gel route

A range of silsesquioxane nanoparticles has been synthesised by a modified Stober method. An aqueous sodium silicate solution was used as a seed for further growth of methyl-, ethyl-, phenyl- and vinyl-modified silica spheres. Particles with diameters in the range 60 - 180 nm were prepared by hydrolysis and condensation reactions of organotrimethoxysilane precursors in a mixture of water, ammonia and ethanol at room temperature. The materials prepared in this study have relatively low specific surface areas and average pore diameters typical of mesoporous solids. The results suggest that the mechanism for the formation of the particles is primarily aggregation and monomer addition.