Preparation of comb-like styrene grafted silica nanoparticles

Comb-like polystyrene grafted silica nanoparticles (c-PS-SNs) were prepared by the following steps: (a) methacryloxypropyl silica nanoparticles (MPSNs) were used as macromonomer and free radical copolymerized with 4-vinyl benzyl chloride (VBC) by a solution polymerization method; (b) the product of (A), poly(4-vinyl benzyl chloride) grafted silica nanoparticle (PVBC-SN) was separated and then used as a macro-initiator for the surface-initiated atom transfer radical polymerization (SI-ATRP) of styrene catalyzed by the complex of Cu(I)Br and 2,2'-bipyridyl (bipy) in toluene solutions. The structurally well-defined polymer chains were grown from the nanoparticle surfaces to yield particles composed of a silica core and a well defined, densely grafted outer comb-like PS layer. A percentage of grafting (PG%) (the weight ratio of the PS grafted with that of the silica charged) of more than 80% was achieved after a polymerizing time of 5 hr.