The radical graft polymerization of vinyl monomers, such as styrene and methyl methacrylate, initiated by azo groups introduced onto silica nanoparticle and carbon black surfaces in room temperature ionic liquid (IL) were investigated. In this work, 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF6]) was used as IL. The percentage of polystyrene and poly(methyl methacrylate) grafting onto silica nanoparticle and carbon black increased with increasing reaction time. The percentage of grafting in IL was much larger than that in 1,4-dioxane. The molecular weight of polystyrene grafted onto the silica surface in IL was almost equal to that in 1,4-dioxane. The result indicates that the amount of grafted polystyrene in IL is five times that in 1,4-dioxane. This may be due to the fact that lifetime of the surface radical formed by the group of azo is prolonged because of high viscosity of IL. Therefore, the surface azo groups were effectively used as initiating sites for the graft polymerization. In addition, the reduction of waste solvent was achieved by use of IL as reaction solvent, because unreacted monomer could be removed under vacuum after the reaction and the reuse of IL was easily achieved. (c) 2006 Wiley Periodicals, Inc.