Preparation of Surface-Wrinkled Silica-Polystyrene Colloidal Composite Particles

In this work, we report a facile emulsion swelling route to prepare surface-wrinkled silica-polystyrene (SiO₂-PS) composite particles. Submicrometer-sized, near-spherical SiO₂-PS composite particles were first synthesized by dispersion polymerization of styrene in an ethanol/water mixture, and then, surface-wrinkled SiO₂-PS particles were obtained by swelling the SiO₂-PS particles with a toluene/water emulsion and subsequent drying. It is emphasized that no surface pretreatment on the SiO₂-PS composite particles is required for the formation of the wrinkled surface, and the most striking feature is that the surface-wrinkled particle was not deformed from a single near-spherical SiO₂-PS composite particle but from many ones. The influence of various swelling parameters including toluene/particle mass ratio, surfactant concentration, stirring rate, swelling temperature, swelling time, and silica size on the morphology of the composite particles was studied. This method represents a new paradigm for the preparation of concave polymer colloids.