Preparation of Stereoregular Branched Polymers of Metharcrylate and Their Properties

1)以相应的活性PMMA阴离子为原料，合成了含甲基丙烯酰基的等规和间规PMMA大分子单体。用1，1-二苯基己基锂在四氢呋喃中的活性聚合体系和t-C_4 H_9 MgBr在甲苯中的活性聚合体系成功地进行了大分子单体与甲基丙烯酸甲酯和甲基丙烯酸乙酯的阴离子共聚。接枝聚合物的侧链和主链均具有立构规整性。大分子单体的阴离子均聚反应也可以得到主链有规立构的梳形PMMA。由于确定的端基结构，1H NMR分析可以确定几个重要的结构特征，包括分支数，组成和分子量。2）全同立构和间同立构PMMA活性阴离子与二甲基丙烯酸酯反应，得到具有立构规整PMMA臂的星星聚合物。与乙二醇二甲基丙烯酸酯的反应仅在全同立构PMMA阴离子用于 ...更多信息 二胺的存在。间同立构PMMA阴离子与二甲基丙烯酸丁二醇酯反应生成星星状聚合物。该星星聚合物的分子量达到一百万。通过对星星聚合物的臂数和分子量变化的分析，证明了在形成星星聚合物的过程中，分子间发生了星-星星连接反应，形成了更高分子量的星星聚合物。接枝PMMA在其主链和侧链中具有相反的立体构型，在丙酮中进行分子内立体络合物的形成，导致异常大的Huggins系数。梳形PMMA的粘度与分子量的关系表明，在临界分子量范围内，梳形PMMA的结构由星形构象转变为梳形构象，这与梳形聚合物的立构规整性有关。星星型PMMA的粘度也表现出明显的立构规整度依赖性，全同星星型PMMA的粘度大于间同型PMMA。少

1) Isotactic and syndiotactic PMMA macromonomers having methacryloyl group were prepared from the corresponding living PMMA anions. Anionic copolymerization of the macromonomers with methyl and ethyl methacrylate was successfully carried out by using two living polymerization systems ; 1,1-diphenylhexyllithum in tetrahydrofuran and t-C_4H_9MgBr in toluene. The obtained graft polymers were found stereoregular both in their side chains and main chain. Anionic homopolymerization of the macromonomer was also possible to afford comb PMMA with stereoregular main chain. Owing to the defined end-group structure, 1H NMR analysis allows the determination of several important structural features including number of branches, compositions, and molecular weight.2) Isotactic and syndiotactic PMMA living anions were reacted with dimethacrylate to obtain star polymers with stereoregular PMMA arms. The reaction with ethylene glycol dimethacrylate proceeded only when the isotactic PMMA anion was used in … More the presence of diamines. The syndiotactic PMMA anion gave a star polymer when reacted with butane-1,4-diol dimethacrylate. The molecular weight of the star polymer reached one million. During the formation of the star polymer, intermolecular star-star linking reaction occurred to form higher molecular weight star polymers, as evidenced from the analysis on the change in the number of arms and molecular weight of the star polymers.3) Several characteristic properties of stereoregular branched PMMA were examined. Graft PMMA having opposite stereoregularities in its main chain and side chains underwent intramolecular stereocomplex formation in asetone, leading to an unusually large Huggins' coefficient. Moecular-weight dependence of viscosity of comb PMMA exhibited the structural change from star-like conformation to comb-like one at critical molecular weight range, which was affected by the stereoregularity of the comb polymer. Viscosity of star PMMA also showed evidently the tacticity dependence, the isotactic star PMMA having larger viscosity than the syndiotactic one. Less