Syntheses of raspberrylike silica/polystyrene materials

Raspberrylike hybrid organic-inorganic materials consisting of spherical silica beads supporting smaller polystyrene particles were prepared through a heterophase polymerization process. In a first step, micrometer-sized silica particles were synthesized according to procedures inspired from the literature. In a second step, a poly(ethylene glycol) macromonomer was adsorbed on the surface of the silica beads. Finally, polymerization of styrene was achieved in water with a nonionic surfactant as an emulsifying agent and sodium persulfate as an initiator. Scanning and transmission electron microscopies show that the presence of the macromonomer on the surface of the silica particles is a determining parameter in order to get the raspberrylike morphology.