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高分子化学成总复习
Chapter 5 Ionic polymerization Cationic polymerization is limited to those monomers with electron-releasing substituents such as alkoxy, phenyl, vinyl and 1,1-dialkyl for example, butylene, alkoxy alkene, conjugated alkene Anionic polymerization takes place with monomers possessing electro-withdrawing groups such as nitrile, carboxyl, phenyl, and vinyl 共轭烯烃类单体可进行自由基、阳离子、阴离子聚合 会判断哪些单体能进行自由基、阳离子、阴离子聚合 根据反应条件中给出的引发剂种类即能判断聚合反应是自由基、阳离子或阴离子聚合 Cationic polymerization: Lewis酸 Lewis acid Anionic polymerization: Lewis碱 (alkali metal, metal alkyl) Living anionic polymerization why anionic polymerization can be “living”? 活性聚合物是指在链增长反应中,活性链直到单体全部耗尽仍保持活性的聚合物,再加入单体还可继续引发聚合,聚合的分子量继续增加。 在阴离子聚合反应中,带有相同电荷的活性链离子不能发生双基终止;活性链负碳离子的反离子常为金属离子,它一般不能夺取链中的某个原子或H+而终止;活性链通过脱去H-离子发生链终止又很困难,所以当体系中无引起链转移或链终止的杂质时,实际上是无终止聚合,即活性聚合。 Why autoacceleration will not occur in ionic polymerization? 活性增长种带电荷,同种电荷相斥,因此无双基终止,不会发生自动加速效应 why the rate of anionic polymerization is larger than that of radical polymerization? 活性增长种的浓度高;无终止。 离子对增长种的结合形式及其活性 In non-polar solvents, extensive association takes place at high butyllithium concentrations, the initiation and propagation rates are found to be proportional to only the 1/6 and 1/2 powers of butyllithium concentration respectively. This result has been interpreted in terms of the association equilibria with the initiator and propagating ion pairs in equilibria with the corresponding hexamer and dimer 会判断阴离子活性聚合用于制备嵌段共聚物时的单体加料顺序(从单体结构判断) Distinguishing between radical, cationic, and anionic polymerizations 如分子量和聚合时间的关系、引发剂、转化率和聚合时间的关系等 Ring-opening polymerization 环状单体在引发剂作用下形成线型聚合物的过程。 Polymerizability (容易开环聚合的程度): 3, 4 8 7, 5 开环聚合的性质? Chapter 6 Coordination polymerization Composition of Ziegler-Natta catalysts ( Ziegler-Natta催化剂的组成) Ziegler-Natta catalysts are usually composed of main catalyst and co-catalyst: Compounds of Group IV-VIII transition metal: (主引发剂是IV-VIII族过渡金属化合物) Co-catalyst: Group
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