Adsorption of Silica Nanoparticles onto Poly(N-vinylpyrrolidone)-Functionalized Polystyrene Latex.

This paper presents a more general method to prepare silica-coated polystyrene (PS) particles with minimal excess silica by adsorption, highlighting the role of poly(N-vinylpyrrolidone) (PVP). The method is based on the addition of small silica nanoparticles onto submicrometer-sized near-monodisperse polymer latex particles under the conditions of monolayer silica coverage of the latex surface. Either a cationic or an anionic initiator could be used in the PVP-involved emulsion polymerization to prepare PS particles, and the adsorption was conducted successfully either under acidic or basic conditions. Neither a cationic initiator nor a basic condition is a prerequisite for the adsorption process, which should be related to the much stronger interaction between PVP and the silica surface. This method is expected to substantially extend the adsorption conditions of polymer-silica colloidal nanocomposite syntheses.