Radical Polymerization Of Methyl Ethacrylate In The Presence Of 1,1-Diphenylethylene And Preparation Of PMMA-b-PtBA Block Copolymers

The radical polymerization of methyl methacrylate(MMA) in the presence of 1,1-diphenylethylene(DPE) with azodiisobutyronitrile(AIBN) as initiator was investigated in this study, and PMMA-b-PtBA block copolymers were prepared by using PMMA precursors obtained in the presence of different molar ratios of DPE.The polymerization process of MMA in the presence of DPE, the structure of PMMA precursors and the molecular weight of PMMA-b-PtBA block copolymers were characterized by GPC,1H-NMR,13C-NMR, FT-IR and ESI-MS. Effect of molar ratios of DPE on the radical polymerization of MMA and the block copolymers was investigated.The results showed that, the radical polymerization of MMA in the presence of DPE possessed characteristic of living polymerization to some extent:polymerization rate and reaction time present linear relationship, the molecular weight of polymer was increased with the increase of monomer conversion and the molecular weight distribution was narrow; the conversion of monomer at the same time and the molecular weight of polymer at the same monomer conversion were decreased with the increase of DPE. The main characteristic structure of PMMA precursors were that only one DPE unit incorporated in the main chain which came from coupling termination between DPE end chain radicals and PMMA chain radicals. PMMA-b-PtBA block copolymers were prepared by using PMMA polymers as precursors which were prepared from DPE system, and the PMMA precursors which were prepared by higher molar ratios of DPE possessed better controllable ability to block copolymers, the conversion of monomer at the same time was increased with the increase of DPE at the polymerization of MMA. The mechanism of the polymerization of MMA in the presence of DPE was proposed recording to the structure of PMMA precursors:the C-C bond of PMMA precursors which came from the coupling termination of DPE was broken and two radicals were generated, one was living radicals which could be polymerized or blocked with monomers and another radicals was stable radicals which could occur reversible termination.