Recent Advances in Cationic Polymerization
Recent Advances in Cationic Polymerization
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阳离子聚合的最新进展
DOI：
10.1007/bfb0050367
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发表时间：
1964
影响因子：
2.4
通讯作者：
A. W. Langer
中科院分区：
文献类型：
--
作者：
J. Kennedy;A. W. Langer
齐格勒和他的同事们发现和发展了一类广泛的催化剂，称为配位阴离子催化剂。他们对丁二烯与锂（777）和丁基锂（178—182a）以及乙烯与丁基锂（183）和三乙基铝（184—186）的聚合的开创性研究是简单有机金属催化剂配位阴离子聚合的经典例子，他们对有机金属-过渡金属“复合物”催化剂（187）的发现开创了立体定向催化的时代。12~ ATTA和他的同事们在扩大配位阴离子催化的范围和应用、机理研究以及新型立体规则聚合物的制备和表征方面做出了许多贡献（188）。最近，Vandenberg（189）开发了一种密切相关的催化剂，可以通过配位阳离子机制引发合适单体的聚合。有充分的理由相信，这是双功能催化剂的配位聚合的一个大的新领域的开始。ZIEGLER的发现（187）导致了用于聚合各种单体的催化剂组成的雪崩（170,190—192）。如果将齐格勒型催化剂定义为含有I-III族有机金属化合物（还原性金属化合物）和IV-VIII族过渡金属化合物的催化剂，那么显然有数十万种组合。很明显，它们不可能都具有相似的性质并由单一机制起作用。为了讨论的目的，人们可以尝试通过根据聚合机制对其进行分组来简化这一信息迷宫，尽管大多数机制尚未确定。烷基金属催化剂最突出的特点是立体专一性。从这方面来看整个领域，似乎有一个共同的特征开始出现。这是在加入部分稳定的聚合物链端之前单体与一部分催化剂的配位。配位发生在具有金属成分空轨道的单体的rr电子或孤对电子之间。聚合物链端固定在位置上，并通过简单或复杂的基因离子部分稳定。这种聚合被称为“配位”或“配位”聚合，以强调单体的配位。应该指出，这些术语的先前使用通常意味着催化剂组分的配位或协同聚合机制。
Full credit for the discovery and development of the broad class of catalysts known as coordinated anionic catalysts must go to ZIEGLER and his coworkers. Their pioneering studies on polymerization of butadiene with lithium (777) and butyl lithium (178--182a) and of ethylene with butyl lithium (183) and triethyl aluminum (184--186) are classic examples of coordinated anionic polymerization with simple organometallic catalysts, and their discovery of organometal-transition metal" complex" catalysts (187) ushered in the age of stereospecific catalysis. 12~ ATTA and his large team of coworkers have made many contributions in expanding the scope and utility of coordinated anionic catalysis, in mechanism studies and in the preparation and characterization of new stereoregular polymers (188). Recently Vandenberg (189) has developed closely related catalysts which can initiate polymerization of suitable monomers by a coordinated cationic mechanism. There is every reason to believe that this is the start of a large new area of coordination polymerization with dual function catalysts. ZIEGLER'S discovery (187) led to an avalanche of catalyst compositions for the polymerization of a widevarietyofmonomers (170,190--192). If one defines ZIEGLER-type catalysts as those which contain an organometallic compound (a reducing metal compound) of Groups I-III and a transition metal compound of Groups IV-VIII, it is evident that there are many hundreds of thousands of combinations. It is obvious that these cannot all have similar properties and operate by a single mechanism. One can attempt to simplify this maze of information for discussion purposes by grouping it according to polymerization mechanism even though most of the mechanisms have not been determined with certainty. The most outstanding feature of alkyl metal catalysts is their stereospecificity. Viewing the entire field in this respect, it appears that a single, common feature is beginning to emerge. This is the coordination of monomer with one part of the catalyst prior to the addition of a partially stabilized polymer chain end. The coordination takes place between rr-electrons or lone-pair electrons of the monomer with vacant orbitals of a metal component. The polymer chain end is fixed in position and partially stabilized by either simple or complex gegen-ions. Such polymerizations are referred to as" coordination" or" coordinated" polymerizations to emphasize coordination of monomer. It should be noted that prior usage of these terms frequently implied either coordination of catalyst components or a concerted polymerization mechanism.