Composite particles of silica/poly(dimethylsiloxane)

A simple procedure for the preparation of submicrometer composite particles of silica and poly-(dimethylsiloxane) (PDMS) is described. There are two novel aspects to this preparation: first it is based on the direct entrapment of the polymer within the sol-gel forming silicate matrix, and second, it is the first description of silica/PDMS composite particles where the PDMS is of high molecular weight (36 000-115 000 g/mol). The particles are formed in an emulsion where the hydrophobic phase is the PDMS dissolved in the sol-gel precursor (tetraethoxysilane) with or without tetrahydrofuran, and the polar phase is alkaline ethanol. Identification of the suitable surfactant, DOW-190, was a key step in developing this procedure. Some properties of the new particles are described.