Synthesis and characterization of monodispersed core-shell/polystyrene-silica composite nanospheres as artificial...

Monodispersed core-shell/polystyrene-silica composite nanospheres are synthesized as artificial dusts by a two-step process, the preparation of seed copolymer spheres and the formation of a silica layer on the seed spheres. The poly(styrene-co-MPS) copolymer spheres containing silanol groups are first prepared by emulsion polymerization using 3-(trimethoxysilyl)propyl methacrylate (MPS) as a co-monomer, potassium persulfate (KPS) as a initiator, and sodium dodecyl sulfate (SDS) as a stabilizer. The diameter of the copolymer spheres is in the range of 220-270 nm with very small coefficients of variation (CV), depending on the content of MPS. The thermal property of the copolymer spheres is also improved as the content of silica increases. Later a silica layer is formed on the seed copolymer spheres by a reaction with tetraethylorthosilicate (TEOS) in aqueous solution. The thickness of the silica layer formed is about 4 to 10 nm, which greatly improves the thermal stability of the copolymer spheres.