Synthesis of graft copolymers with polyisobutylene branch chains |
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Authors: | Qing-yuan Li Yi-xian Wu Wen-yan Ma Ri-wei Xu Guan-ying Wu Wan-tai Yang |
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Institution: | State Key Laboratory of Chemical Resource Engineering, Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, Beijing 100029, China |
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Abstract: | The copolymerization of 4-vinylbenzyl chloride (VBC) and vinyl acetate (VAC) was carried out in toluene at 75℃ via radical polymerization using 2,2'-azo-bis-(isobutyronitrile) (AIBN) as an initiator. The random copolymers of poly(4-vinylbenzyl chloride-co-vinyl acetate) (P(VBC-co-VAC)) with number average molecular weight (Mn) from 2000 to 6900, relatively narrow molecular weight distribution (MWD, Mw/Mm ca. 2.0) and with different copolymer composition of 4-vinylbenzyl chloride (VBC) from 17 mol% to 62 mol% could be obtained. The P(VBC-co-VAC) copolymers with an average number of 7 to 13 initiating sites of benzyl chloride per macromolecule could be used for the cationic polymerization of isobutylene (IB). The cationic polymerizations of IB were further conducted by using P(VBC-co-VAC) copolymers as macroinitiators in conjunction with TiCU at-40℃ in CH2C12. The effects of VBC/TiCl4 (molar ratio) on monomer conversion, Mn and MWD of the resultant copolymers were investigated under 3 sets of conditions. It is found that P(VBC-co-VAC)-g-PIB copolymers with relatively narrow MWD (MJMn ca. 2.0) and with terminal terf-chlorine functional groups in branched PIB chains could be successfully synthesized when VBC/TiCl4 (molar ratio) was set in the range from 0.10 to 1.12. The unimodal GPC curve of the P(VBC-co-VAC)-g-PIB copolymers by RI detector was almost in harmony with the GPC curve by UV detector. The TEM image of the P(VBC-co-VAC)-g-PIB copolymer stained by RuO indicated that the copolymer formed a two-phase morphology with P(VBC-co-VAC)-rich domains of 20-100 nm in size tethered by PIB branch segments. |
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Keywords: | Isobutylene Cationic polymerization Macroinitiator Graf) copolymerization |
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