Synthesis of vinyl polymer-silica colloidal nanocomposites prepared using commercial alcoholic silica sols.

The surfactant-free synthesis of vinyl polymer−silica nanocomposite particles has been achieved in aqueous alcoholic media at ambient temperature in the absence of auxiliary comonomers. Styrene, methyl methacrylate, methyl acrylate, n-butyl acrylate, and 2-hydroxypropyl methacrylate were homopolymerized in turn in the presence of three commercially available ultrafine alcoholic silica sols. Stable colloidal dispersions with reasonably narrow size distributions were obtained, with silica contents of up to 58% by mass indicated by thermogravimetric analysis. Particle size distributions were assessed using both dynamic light scattering and disk centrifuge photosedimentometry. The former technique indicated that the particle size increased for the first 1−2 h at 25 °C and thereafter remained constant. Particle morphologies were studied using electron microscopy. Most of the colloidal nanocomposites comprised approximately spherical particles with relatively narrow size distributions, but in some cases more po...