In-situ emulsion polymerization of styrene in the presence of nano-SiO_2

Polystyrene/SiO_2 microcapsule was prepared through in-situ emulsion polymerization of styrene in the presence of nano-SiO_2. The effects of the styrene concentration, styrene/SiO_2 ratio, solid content, addition modes of styrene and the initiator, and polymerization temperature on the conversion of styrene and the diameter of the PS/SiO_2 microcapsule were studied. It was found that the microcapsule diameter was mainly affected by the styrene/SiO_2 ratio, and gradually decreased with increase of polymerization time. It shows that the nano-SiO_2 aggregate could be cleaved and thus separated by the insertion of styrene and polystyrene into the crevices within the aggregate during the in-situ emulsion polymerization and result in nanometer-grade dispersion in polystyrene.