Cobalt Mediated Radical Polymerization of 4-Bromo-2,6-Dimethyl Phenol and Its Copolymerization with Poly(dimethyl siloxane) in the Presence of Co(acac)2: DMF Catalyst

Abstract

Novel well-defined poly(phenylene oxide) (PPO)-based block copolymers were polymerized from 4-bromo-2,6-dimethylphenol (BDMP) in the presence of a cobalt acetylacetonate (Co(acac) 2 ) catalyst with dimethyl formamide (DMF) as a ligand and initiated with benzoyl peroxide (BPO) at 60°C in a novel controlled copolymerization reaction within a good yield. The monomer copolymerized with vinyl acetate (VAc), poly(methyl methacrylate)-b-poly(dimethyl siloxane)-b-poly (methyl methacrylate) (PMMA-b-PDMS-b-PMMA) and polystyrene-b-poly-(dimethyl siloxane)-b-polystyrene (PSt-b-PDMS-b-PSt) triblock copolymers in good yield. Characterization indicated a very narrow molecular weight distribution. The block copolymer indicated a new microstructure of phenylene oxide which was analyzed by proton-nuclear magnetic resonance ( 1 H-NMR), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetriy (DSC) and gel permeation chromatography (GPC). Meanwhile, the number average molecular weights calculated from the 1 H-NMR spectra were in very good agreement with the theoretically calculated values. The DSC results also indicated the successful formation of these new block copolymers.Keyword Poly(dimethyl siloxane) (PDMS) Á Poly(phenylene oxide)s(PPO) Á 4-Bromo-2,6-dimethyl phenol (BDMP) Á Co(acac) 2 catalyst Á Controlled radical polymerization Á Dimethyl formamide (DMF) Á Reactivity ratio Á Poly(methyl methacrylate) (PMMA)