Synthesis of Star Isotactic Polypropylene Using Click Chemistry
Synthesis of Star Isotactic Polypropylene Using Click Chemistry
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DOI：
10.1021/ma1019335
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发表时间：
2010-10
期刊：
影响因子：
5.5
通讯作者：
Huahua Huang;H. Niu;Jin‐Yong Dong
中科院分区：
文献类型：
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作者：
Huahua Huang;H. Niu;Jin‐Yong Dong
导言。具有星形结构的聚合物包含在中心核心连接的多个臂，是最简单的支化拓扑形式之一。对星形聚合物的持续兴趣源于其独特的流变性和机械性能以及显著的高度官能化。1合成星形聚合物，特别是那些具有明确的臂数和长度的星形聚合物，通常采用两种典型的方法之一：通过从多功能引发剂中生长臂来实现核优先；2通过将线性臂前体偶联到多功能连接剂上来实现臂优先。3前一种方法需要使用多功能引发剂，可以同时引发聚合物臂的多方向“活”生长，与“臂优先”方法所取得的巨大成就相比，前者的成功要小得多。通过结合“活性”聚合技术，包括传统的“活性”阴阳离子聚合和新近发展的“活性”/可控自由基聚合(CRP)，以及高效的偶联反应，“臂优先”方法被开发并广泛应用于合成定义明确的星形聚合物。4在各种偶联反应中，铜(I)介导的叠氮炔环加成反应(CuAAC)是最常用的点击反应，由于其非凡的可靠性和对官能团的耐受性而得到了极大的关注。6与由各种单体(包括苯乙烯和取代的苯乙烯、甲基丙烯酸酯和丙烯酸酯)合成星形聚合物的大量文献相比，7星形聚烯烃的合成报道要少得多。聚烯烃占世界热塑性塑料产量的一半以上，大多是通过配位聚合机理制备的。8星形聚烯烃因其独特的流变性而备受关注，是研究支化结构与性能关系的模型体系。9然而，大多数关于星形聚烯烃的研究仅限于少数几种类型，即星形聚异戊二烯、星形聚丁二烯及其氢化聚合物，它们是由异戊二烯和丁二烯活性阴离子聚合而成的。10到目前为止，叶和他的同事只报道了一个通过配位聚合机制制备星形聚烯烃的例子。11他们成功地开发了一种新型的三核Pdrdiimine络合物，该络合物能够通过乙烯“活性”配位聚合“核优先”合成三臂星形聚乙烯。
Introduction. Polymers with star-shaped structure containing multiple arms connecting at the central core are among the simplest form of branched topologies. The constant interest in star polymers stems from their unique rheological and mechanical properties and a significantly high degree of functionality. 1 Synthesis of star polymers, especially those of well-defined arm number and length, often utilizes one of two typical approaches:“core-first” by growing arms from a multifunctional initiator; 2 “arm-first” by coupling linear arm precursors onto a multifunctional linking agent. 3 The former approach requiring the use of a multifunctional initiator that can simultaneously initiate multidirectional “living” growth of polymer arms shows much less success compared to the great achievement with the “arm-first” approach. The “arm-first” approach for the synthesis of well-defined star polymers is developed and widely used by the combination of “living” polymerization techniques, including the traditional “living” anionic and cationic polymerization and the recently developed “living”/controlled radical polymerization (CRP), and the efficient coupling reactions. 4 Among various coupling reactions, the copper (I)-mediated azideralkyne cycloaddition reaction (CuAAC), 5 which is the most popular click reaction, has gained a great deal of attention due to its extraordinary reliability and functional group tolerance. 6 Compared to the large number of literatures on synthesis of star polymers from various monomers including styrene and substituted styrenes, methacrylates, and acrylates, 7 the synthesis of star polyolefins is covered by much fewer reports. Polyolefins account for more than half of world production of thermoplastics, which are mostly prepared by the coordination polymerization mechanism. 8 Star polyolefins have been attracting much attention due to the unique rheological properties and that they represent model systems for the research on the relationship between branch structure and performing behavior. 9 However, most studies on star polyolefins are limited to only a few types, that is, star polyisoprene, star polybutadiene, and their hydrogenated polymers, which are prepared by living anionic polymerization of isoprene and butadiene. 10 To date, only one example of the preparation of star polyolefins through the coordination polymerization mechanism was reported by Ye and co-workers. 11 They successfully exploited a novel trinuclear Pdrdiimine complex, which enables the “core-first” synthesis of three-arm star polyethylene via ethylene “living” coordination polymerization.