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首页> 外文期刊>Polymers >Synthesis of Isotactic- block -Syndiotactic Poly(methyl Methacrylate) via Stereospecific Living Anionic Polymerizations in Combination with Metal-Halogen Exchange, Halogenation, and Click Reactions
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Synthesis of Isotactic- block -Syndiotactic Poly(methyl Methacrylate) via Stereospecific Living Anionic Polymerizations in Combination with Metal-Halogen Exchange, Halogenation, and Click Reactions

机译：立体定向活性阴离子聚合结合金属-卤素交换，卤化和点击反应合成等规嵌段-间规聚甲基丙烯酸甲酯

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Isotactic ( it -) and syndiotactic ( st -) poly(methyl methacrylate)s (PMMAs) form unique crystalline stereocomplexes, which are attractive from both fundamental and application viewpoints. This study is directed at the efficient synthesis of it - and st -stereoblock ( it - b - st -) PMMAs via stereospecific living anionic polymerizations in combination with metal-halogen exchange, halogenation, and click reactions. The azide-capped it -PMMA was prepared by living anionic polymerization of MMA, which was initiated with t -BuMgBr in toluene at ?￠????78 ???°C, and was followed by termination using CCl 4 as the halogenating agent in the presence of a strong Lewis base and subsequent azidation with NaN 3 . The alkyne-capped st -PMMA was obtained by living anionic polymerization of MMA, which was initiated via an in situ metal-halogen exchange reaction between 1,1-diphenylhexyl lithium and an ???±-bromoester bearing a pendent silyl-protected alkyne group. Finally, copper-catalyzed alkyne-azide cycloaddition (CuAAC) between these complimentary pairs of polymers resulted in a high yield of it - b - st -PMMAs, with controlled molecular weights and narrow molecular weight distributions. The stereocomplexation was evaluated in CH 3 CN and was affected by the block lengths and ratios.
机译：等规（it-）和间规（st-）聚（甲基丙烯酸甲酯）（PMMA）形成独特的结晶立体复合物，从基本和应用的角度来看，它们都具有吸引力。这项研究的目的是通过立体有择的活性阴离子聚合以及金属-卤素交换，卤化和点击反应，有效合成st和-stereoblock（it-b-st-）PMMA。通过MMA的活性阴离子聚合反应制备叠氮化物封端的it -PMMA，该聚合反应是在叔丁醇中于78℃在甲苯中用t -BuMgBr引发的，然后用CCl 4卤化终止剂在强Lewis碱的存在下和随后与NaN 3的叠氮化。炔烃封端的st -PMMA是通过MMA的活性阴离子聚合获得的，该聚合是通过1,1-二苯基己基锂与带有侧基甲硅烷基保护的炔烃的±-溴酸酯之间的原位金属-卤素交换反应引发的组。最后，这些互补的聚合物对之间的铜催化的炔-叠氮化物环加成（CuAAC）导致了其高产率-b-st -PMMA，具有可控制的分子量和窄的分子量分布。在CH 3 CN中评估立体配合物，并受嵌段长度和比例的影响。

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