Preparation of Stereoregular Branched Polymers of Metharcrylate and Their Properties

1)从相应的活性PMMA阴离子出发，合成了具有甲基丙烯酰基的等规型和间规型PMMA大分子单体。用四氢呋喃中的1，1-二苯基己基锂和甲苯中的t-C4H9MgBr两种活性聚合体系，成功地实现了大单体与甲基丙烯酸甲酯和甲基丙烯酸乙酯的阴离子共聚。所得接枝聚合物的侧链和主链都是立体规则的。大单体的阴离子均聚也可以得到具有立体规则主链的梳状PMMA。由于定义了端基结构，1H核磁共振分析可以确定几个重要的结构特征，包括支链数量、组成和分子质量。2)等规型和间规PMMA活性阴离子与二甲基丙烯酸酯反应，得到具有立体规则PMMA臂的星形聚合物。只有在…中使用等规聚甲基丙烯酸甲酯阴离子时，才能与乙二醇二甲基丙烯酸酯反应更多的二胺的存在。间规PMMA阴离子与丁烷-1，4-二甲基丙烯酸酯反应生成星形聚合物。星形聚合物的相对分子质量达到了100万。在星形聚合物的形成过程中，发生了分子间的星形-星形连接反应，形成了较高相对分子质量的星形聚合物，分析了星形聚合物的臂数和相对分子质量的变化。3)研究了立体正规支化PMMA的一些特性。主链和侧链具有相反立体规律性的接枝PMMA在ASTone中形成了分子内立体络合物，导致了异常大的Huggins系数。在临界相对分子质量范围内，梳状PMMA的粘度随分子量的变化表现出由星状构象向梳状构象的结构变化，这受梳状聚合物立构规整性的影响。星形PMMA的粘度也表现出明显的规整性依赖关系，全同立构PMMA的粘度大于间同立构PMMA。较少

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