Preparation of Dimpled Polystyrene–Silica Colloidal\nNanocomposite Particles

Abstract

Preparation\nof polymer–silica colloidal nanocomposite particles\nwith concave shape is challenging and seldom reported. This paper\npresents a novel and facile method to prepare dimpled polymer–silica\nnanocomposite particles with a thin silica shell through the judicious\ncombination of alcoholic dispersion polymerization and the decane\nevaporation method. Submicrometer-sized polystyrene–silica\n(PS–SiO₂) nanocomposite particles were first prepared\nby dispersion polymerization of styrene in methanol in the presence\nof a methanolic silica sol, and then dimpled PS–SiO₂ particles were prepared by heating the near-spherical PS–SiO₂ particles dispersed in methanol/water media in the presence\nof decane and subsequent cooling. The effects of different heat treatment\nparameters, such as methanol/water ratio, stirring temperature, and\nstirring rate on the formation of the nanocomposite particles were\ninvestigated. Optimization of the heating conditions allowed ∼100%\nof dimpled particles to be achieved with one dimple on each particle.\nMoreover, calcination of the dimpled PS–SiO₂ nanocomposite\nparticles led to the formation of hollow dimpled particles with a\nthin silica shell. This method is expected to enrich the shapes of\npolymer–silica nanocomposite particles.