Synthesis and Characterization of Poly(methyl methacrylate)-b-Polystyrene/TiO2 Nanocomposites Via Reversible Addition-Fragmentation Chain Transfer Polymerization

A diblock copolymer, poly(methyl methacrylate)-b-polystyrene (PMMA-b-PS), was grafted onto the surface of nano-titania (nano-TiO₂) successfully via reversible addition-fragmentation chain transfer (RAFT) polymerization. The surface of TiO₂ nanoparticles was modified initially by attaching dithioester groups to the surface using silane coupling agent 3-(chloropropyl)triethoxy silane and sodium ethyl xanthate. The polymerization of methyl methacrylate and styrene were then initiated and propagated on the TiO₂ surface by RAFT polymerization. The resulting composite nanoparticles were characterized by means of XPS, FT-IR, ¹H NMR and TGA. The results confirmed the successful grafting of poly(methyl methacrylate) (PMMA) and diblock copolymer chains onto the surface of TiO₂. The amount of PMMA grafted onto the TiO₂ surface increased with the polymerization time. Moreover, the kinetic studies revealed that the ln([M]₀/[M]), where [M]₀ is the initial and [M] is the time dependent monomer concentrations, increased linearly with the polymerization time, indicating the living characteristics of the RAFT polymerization.