Polymer6 配位聚合 Coordination Polymerization.pptVIP

Chap.6 配位聚合 Coordination Polymerization 6.1 引言 6.2 聚合物的立体异构现象 6.3 烯烃的Ziegler-Natta聚合 6.4 共轭二烯的立体定向聚合 6.5 配位聚合的工业应用 6.1 引言 Introduction 6.2 聚合物的立体异构现象 Stereoisomerism in Polymers 6.2.1 立体异构类型 Types of Stereoisomerism in Polymer Stereoisomerism 构造 constitution 构型 configuration 构象 conformation 结构 structure 对映异构体 enantiomers Constitutional isomerism is encountered when polymers have the same overall chemical composition but atom or groups of atoms are connected in different order. Isomeric polymers can also be obtained from a single monomer. A. 单取代烯烃 Monosubstituted Ethylenes 立构规整性 Tacticity Tacticity 间同（间规）立构 A syndiotactic polymer structure occurs when the configuration of the stereocenter alternates from one repeating unit to the next with the R groups alternately on the opposite sides of the plane of the polymer chain. Tacticity If the R groups on successive stereocenters are randomly distributed on the planar zigzag polymer chain, the polymer does not have order and is termed atactic. (无规的) Tacticity 全同排列对于连续的一对立构中心而言相当于内消旋排列；间 同排列对于连续的一对立构中心而言相当于外消旋排列。 构型重复单元/构型基本单元 The configurational repeating unit is defined as the smallest set of configurational base units that describe the configurational repetition in the polymer. 对于单取代烯烃的全同聚合物，构型重复单元与构型 基本单元相同；对于间同聚合物而言，构型重复单元 则是由两个构型基本单元（一个R-单元连接着一个S- 单元，反之亦然）所组成的片断。 立体定向聚合 ■ Polymerizations that yield tactic structures (either isotactic or syndiotactic) are termed stereospecific polymerizations (立体定向聚合)。 ■ Both isotactic and syndiotactic polypropylenes are achiral as a result of a series of mirror planes (i.e., planes of symmetry) perpendicular to the polymer chain axis. Neither exhibits optical activity. B. 二取代烯烃 Disubstituted Ethylenes Stereoisomerism Stereoisomerism 讨 论 1) 苏式双间同和赤式双间同的结构除了端基有差异外，实际上是一样的。忽略端基，它们可以重叠，也就是说，只有一种双间同聚合物； 2) 前缀: it-, st-, tit-, eit-分别表示全同-、间同-、苏式双间同和赤式双间同。 3) 在所有三种立构规整聚合物中,立构中心均为非手性的.这些聚合物是非光学活性的.双全同聚合物具有正交于主链(轴)的镜面;双间同聚合物具有一个对称的滑动镜面. C. 羰基化合物和开环聚合