Synthesis Of Graft Copolymer Poly (Methyl Methacrylate-co-Hydroxy Ethyl Methacrylate)-graft-Polystyrene And Star-Shaped Polystyrene With Four Arms By Atom Transfer Radical Polymerization

In this dissertation, poly ( methyl methacrylate-co-hydroxyethyl methacrylate) -g-polystyrene graft copolymer and star-shaped polystyrene with four arms were prepared by atom transfer radical polymerization.Firstly, poly (methyl methacrylate-co-hydroxyethyl methacrylate) was prepared by the copoiymerization of methyl methacrylate and hydroxyethyl methacrylate with ethyl 2~bromo-2-methylpropionate as the initiator and CuBr 'bipyridine complex as the catalyst. Secondly, part of the hydroxyl groups pendent on the copolymer chain were transferred into 2-bromo-2-mcthylpropionyl groups by treating this copolymer with 2-bromo-2-melhylpropionyl bromide. Finally, the functional polymer obtained above was used as the macroinitiator to initiate the atom transfer radical polymerization of stvrene and resulted in poly (methyl methacrylate-co-hxdroxy ethyl methacrylale ) -g-polystyrene graft copolymer. The structurc of the copolymer was characterized by H NMR , chemical analyticol method and GPC. Furthermore, the polystyrene grafted chains were cleaved from poly (methyl methacrylate-co-hydroxyethyl methacrylale ) main chain through hydrolysis. The molecule weights and molecule weight distributions of grafted polystyrene chains were obtained by GPC.novel multifunctional initiator cztetra(chloru juimc-ih) 1 benzene was synthesized. It can initiate the atom transfer radicalpolymerization of styrene efficiently, obtained polymers withpredetermined molecular weights and narrow molecular weightdistributions. When the ATRP of styrene was initiated by the mixture of 1-phenylethyl chloride and tetra(chloro)dimethyl benzene in onepot, polystyrenes with bimodal molecular weight distributions wereobtained. Moreover, the ratio of the two peak molecular weights in GPCspectrum was close to the theoretical values, 4/1, showing that tetra(chloro)dimethyl benzene is a tetrafunctional initiator for the ATRPof styrene. Additionallv. the polymerization of styrene was initiated by 1-phenylethyl chloride. benzyl dichloride and letra(chloro)dimethy] benzene respectively under the identical reactionconditions. It was found that when the same initiator concentration wasused. the ratio of the polymerization rate was 1:2:4 approximately, furtherverifying that tetra(ehloro)dimethyl benzene is a tetrafunctionalinitiator for the ATRP of styrene.