Thermosensitive gradient copolymers by living cationic polymerization: Semibatch precision synthesis and stepwise dehydration‐induced micellization and physical gelation
Thermosensitive gradient copolymers by living cationic polymerization: Semibatch precision synthesis and stepwise dehydration‐induced micellization and physical gelation
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DOI：
10.1002/pola.22926
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发表时间：
2008-09
期刊：
影响因子：
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通讯作者：
Ken-ichi Seno;Itsuko Tsujimoto;T. Kikuchi;S. Kanaoka;S. Aoshima
中科院分区：
文献类型：
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作者：
Ken-ichi Seno;Itsuko Tsujimoto;T. Kikuchi;S. Kanaoka;S. Aoshima
在添加碱的情况下，通过活性阳离子聚合合成了具有各种序列分布的热敏强制梯度共聚物。该合成采用半间歇反应方法进行，该方法不利于离子聚合，特别是在使用简单设备时。使用传统的注射器技术引发 2-乙氧基乙基乙烯基醚 (EOVE) 的聚合。引发后，立即使用注射泵以调节的进料速率连续添加 2-甲氧基乙基乙烯基醚 (MOVE)，从而可以控制序列分布。所得的 EOVE 和 MOVE 梯度共聚物在水中经历热诱导缔合，形成具有源自富含 EOVE 链段的疏水核心的胶束。有趣的是，由梯度共聚物获得的胶束的尺寸随着溶液温度的升高而单调减小，而相应的嵌段共聚物的胶束的尺寸没有变化。这种自关联行为可以通过设计瞬时成分的梯度模式来控制。 © 2008 Wiley periodicals, Inc. J Polym Sci Part A：Polym Chem 46：6151–6164，2008
Thermosensitive forced gradient copolymers with various sequence distributions were synthesized by living cationic polymerization in the presence of an added base. The synthesis was conducted using a semibatch reaction method, which is unfavorable for ionic polymerization, especially when a simple apparatus is employed. Polymerization of 2-ethoxyethyl vinyl ether (EOVE) was initiated using a conventional syringe technique. Immediately after initiation, 2-methoxyethyl vinyl ether (MOVE) was continuously added using a syringe pump at regulated feed rates, which allowed control of the sequence distribution. The resulting gradient copolymers of EOVE and MOVE underwent thermally induced association in water, forming micelles with a hydrophobic core derived from EOVE-rich segments. Interestingly, the size of the micelles obtained from gradient copolymers decreased monotonously with increasing solution temperature, while the micelles of the corresponding block copolymers were unchanged in size. This self-association behavior can be controlled by designing the gradient pattern of the instantaneous composition. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6151–6164, 2008