Nucleation of silica Stöber particles in the presence of methacryloxypropyltrimethoxysilane

Resumo

The effect of 3-methacryloxypropyltrimethoxysilane (MPTMOS) on the nucleation of silica particles synthesized in a water−ethanol−ammonia−tetraethoxysilane (TEOS) mixture by the Stöber−Fink−Bohn method has been studied. It has been shown, using atomic force microscopy, that, as the content of MPTMOS in a TEOS + MPTMOS precursor mixture is increased from 0 to 12.5 mol %, the final silica particle size decreases from 470 to 10 nm, because the number of nucleation centers increases by several orders of magnitude. In contrast to TEOS, hydrolysis of MPTMOS yields a smaller amount of deprotonated orthosilicic acid monomers, the condensation of which is hindered by electrostatic repulsion. The polycondensation of electrically neutral products of MPTMOS hydrolysis gives rise to a larger number of nucleation centers in the reaction mixture.