Preparation and characterization of polystyrene/nano-SiO₂ composites

To improve the compatibility between nano-SiO₂ particles and polymeric matrix, and make the surface of nano-SiO₂ functionalized, nano-SiO₂ particles were treated with silane coupling agent (KH-570) and groups of C=C were introduced onto the surface of nano-SiO₂ particles successfully. Polystyrene was further grafted on the treated nano-SiO₂ particles surfaces via emulsion polymerization, and composite particles of SiO₂-PSt, with both monomer conversion and grafting efficiency higher than 80%, were obtained. Influences of the ratio of SiO₂ and KH-570 on monomer conversion and binding efficiency in the polymerization reaction were investigated. The mechanism of silane coupling agent (KH-570) was also discussed. The surface structures, morphologies and the distribution of nano-SiO₂ particles in polystyrene were characterized with FT-IR, TEM and TG. Results indicated that the surface grafting treated by nano-SiO₂ composite particles had an obvious core-shell structure and the thickness of polymer shells was around 20 nm. The aggregated nano-SiO₂ particles were gradually dispersed during the emulsion polymerization.