Initiating systems for nitroxide-mediated ''living'' free radical polymerizations: Synthesis and evaluation
Initiating systems for nitroxide-mediated ''living'' free radical polymerizations: Synthesis and evaluation
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DOI：
10.1021/ma951905d
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发表时间：
1996-07-29
期刊：
影响因子：
5.5
通讯作者：
Devonport, W
中科院分区：
文献类型：
--
作者：
Hawker, CJ;Barclay, GG;Devonport, W
已经制备并评价了用于通过氮氧自由基介导的“活性”自由基程序制备大分子的各种引发系统。该体系可分为两类，单分子引发剂，其中烷基化克里思（2，2，6，6-四甲基哌啶基氧基）衍生物离解以提供引发自由基和稳定自由基，和双分子体系，其中传统的自由基引发剂如BPO或AIBN与克里思结合使用。对于单分子引发剂，发现α-甲基对于“活性"特征是必不可少的，而各种取代基可以置于苯环或β-碳原子上而不影响单分子引发剂的效率。还发现，对于单分子和相应的双分子体系，聚合速率大致相同;然而，单分子引发剂提供了对分子量和多分散性的更好控制。
A variety of initiating systems for the preparation of macromolecules by nitroxide-mediated ''living'' free radical procedures have been prepared and evaluated. The systems can be divided into two classes, unimolecular initiators in which alkylated TEMPO (2,2,6,6-tetramethylpiperidinyloxy) derivatives dissociate to provide both the initiating radical and the stable radical, and bimolecular systems in which a traditional free radical initiator, such as BPO or AIBN, is used in conjunction with TEMPO. For the unimolecular initiators it was found that an alpha-methyl group is essential for ''living'' character, while a variety of substituents could be placed on the phenyl ring or the beta-carbon atom without affecting the efficiency of the unimolecular initiator. It was also found that the rate of polymerization is approximately the same for both the unimolecular and corresponding bimolecular systems; however, the unimolecular initiators afforded better control over molecular weight and polydispersity.