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Development of Living Cationic Polymerization: Novel Methods for Controlled Polymer Synthesis

活性阳离子聚合的进展：可控聚合物合成的新方法

基本信息

批准号：
63470099
负责人：
HIGASHIMURA Toshinobu
金额：
$ 3.26万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

This research project was directed toward three objectives: (a) to establish general principles of living cationic polymerization; (b) to develop new initiating systems for high-temperature living cationic processes; and (c) to expand the scope of living cationic polymerization to a variety of monomers.(a) General Principles of Living Cationic Polyrarization. Living cationic polymerization has been difficult because of the iherent instability of the carbocationic intermediate therein. We theorized that "nucleophilic stabilization" of the unstable growing carbocation might lead to living pationic polymerization. On the basis of this hypothesis, we have proposed two methods to stabilize the growing carbocations; (A) stabilization by a suitably nucleophilic counteranion; and (B) stabilization by a added weak Lewis base. Both principles have been shown valid and thus led to a variety of new initiating systems.(b) High-Temperature Living Cationic Polymerization in the Presence of Added Base … More s. In general, strongly acidic metal halides (like EtAlCl_2) cannot induce living cationic polymerization, because they generate counteranions too weakly nucleophilic to stabilize the growing carbocations. Our principle (B) turned out specifically effective for these systems; and addition of such weak Lewis bases as esters, ethers, and pyridine derivatives was found to stabilize the growing cation through nuclephilic interaction and thereby allows living cationic polymerization of vinyl ethers at temperatures as high as +70 ﾟC.(c) Living Cationic Polyrarization of Styrene Derivatives. With use of the hydrogen iodide/zinc iodide (HI/ZnI_2) initiating system, which is based on our principle (A), living cationic polymerization has been achieved not only for vinyl ethers but also for styrene derivatives. Specifically, well-defined living polymers were obtained from p-t-butoxystyrene even at room temperature, though it carries an acid-sensitive alkoxyl group. Hydrolysis of the polymer led to poly(p-vinylphenol) of a controlled molecular weight. Block copolymers of p-t-butoxystyrene with various vinyl monomers were also synthesized. Less

该研究项目有三个目标：（a）建立活性阳离子聚合的一般原理;（B）开发用于高温活性阳离子过程的新引发体系;以及（c）将活性阳离子聚合的范围扩展到各种单体。(a)活性阳离子聚合的一般原理。活性阳离子聚合一直是困难的，因为其中的碳阳离子中间体的固有不稳定性。我们推测，不稳定增长的碳正离子的“亲核稳定化”可能导致活性阳离子聚合。在此假设的基础上，我们提出了两种方法来稳定增长的碳正离子：（A）稳定的适当亲核抗衡阴离子;（B）稳定的添加弱刘易斯碱。这两种原理都被证明是有效的，并由此产生了各种新的起爆系统。(b)外加碱存在下的高温活性阳离子聚合 ...更多信息 S.一般来说，强酸性金属卤化物（如EtAlCl_2）不能诱导活性阳离子聚合，因为它们产生的抗衡阴离子亲核性太弱，不能稳定生长的碳阳离子。我们的原理（B）被证明对这些体系特别有效;并且发现添加诸如酯、醚和吡啶衍生物等弱刘易斯碱可以通过亲核相互作用稳定增长的阳离子，从而允许乙烯基醚在高达+70 ° C的温度下进行活性阳离子聚合。(c)苯乙烯衍生物的活性阳离子聚合。采用基于（A）原理的碘化氢/碘化锌（HI/ZnI_2）引发体系，不仅实现了乙烯基醚的活性阳离子聚合，而且实现了苯乙烯衍生物的活性阳离子聚合。具体地说，即使在室温下，也可以从对叔丁氧基苯乙烯得到定义明确的活性聚合物，尽管它带有酸敏感的烷氧基。聚合物的水解导致受控分子量的聚（对乙烯基苯酚）。还合成了对叔丁氧基苯乙烯与各种乙烯基单体的嵌段共聚物。少