Fast living cationic polymerization of vinyl ethers with iron(III) chloride in the presence of a cyclic ether: Most active and environmentally benign catalyst for the living cationic polymerization of vinyl ethers
Fast living cationic polymerization of vinyl ethers with iron(III) chloride in the presence of a cyclic ether: Most active and environmentally benign catalyst for the living cationic polymerization of vinyl ethers
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DOI：
10.1002/pola.21632
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发表时间：
2006-10
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影响因子：
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通讯作者：
Arihiro Kanazawa;Yumi Hirabaru;S. Kanaoka;S. Aoshima
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文献类型：
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作者：
Arihiro Kanazawa;Yumi Hirabaru;S. Kanaoka;S. Aoshima
我们已经合成了定义明确的刺激响应性聚（乙烯基醚）的活性阳离子聚合反应中添加碱的存在下，1，我们已经证明，高灵敏度的相分离和物理凝胶化，可以实现与oxydrocarbon侧链，2羧基，3或azo groups 4的聚合物的水溶液，在响应温度，pH值，或光，分别。典型的引发体系由EtxAlCl 3·xAlCl 3（x1/4，1.5）和添加的碱（例如酯或醚）组成。6该系统不仅生产线性嵌段共聚物，而且生产具有窄分子量分布（MWD）的星形聚合物。7这些体系的一个问题是极性单体与侧链中的杂原子的聚合反应进行得非常缓慢。最近用SnCl 4作为刘易斯酸催化剂克服了这一困难。SnCl 4/EtxAlCl 3·x引发体系诱导快速活性阳离子聚合，8其进行速度比单独使用EtxAlCl 3·x的反应快1000倍以上。此外，即时活性阳离子聚合，在几秒钟内完成，在较弱的添加碱的存在下实现。这些结果表明，对于活性阳离子聚合，可能存在刘易斯酸和添加的碱的其它适当组合。因此，这一重新发现鼓励我们调查各种组合的刘易斯酸和添加碱的活性聚合。在用于阳离子聚合的许多常见刘易斯酸中，10我们从卤化铁（III）（FeX 3）开始，因为它们在工业用途：它们易于处理，具有低毒性，并且经济有效。[11]自20世纪40年代以来，已经有几项研究报道了通过各种方法测定的FeCl 3的酸度，它被认为是一种强酸。[12]例如，与AlCl 3和SnCl 4相比，根据与羰基相互作用的程度，酸度以AlCl 3> FeCl 3> SnCl 4的顺序降低。[13]在羰基化合物存在下，氯代烷烃形成碳阳离子的反应中观察到不同的顺序，FeCl 3> SnCl 4> AlCl 3。14由于其强酸性和与羰基化合物的较小相互作用，FeCl 3预期在添加碱的情况下诱导快速活性阳离子聚合，其速率甚至将大于SnCl 4。虽然有几个猫的例子-
We have synthesized well-defined stimuli-responsive poly (vinyl ether) s by living cationic polymerization in the presence of an added base, 1 and we have demonstrated that highly sensitive phase separation and physical gelation can be achieved with aqueous solutions of polymers with oxyethylene side chains, 2 carboxy groups, 3 or azo groups4 in response to the temperature, pH, or light, respectively. A typical initiating system consists of EtxAlCl3Àx (x ¼ 1, 1.5) and an added base, such as an ester5 or ether. 6 This system produces not only linear block copolymers but also star-shaped polymers with a narrow molecular weight distribution (MWD). 7 One problem with these systems is that the polymerization reactions of polar monomers with heteroatoms in the pendant proceed very slowly. This difficulty was recently overcome with SnCl4 as a Lewis acid catalyst. The SnCl4/EtxAlCl3Àx initiating system induced fast living cationic polymerization, 8 which proceeded more than 1000 times faster than the reaction with EtxAlCl3Àx alone. Furthermore, instant living cationic polymerization, completed in a few seconds, was achieved in the presence of a weaker added base. 9 These results suggest that there could be other appropriate combinations of Lewis acids and added bases for living cationic polymerization. Therefore, this rediscovery encouraged us to survey various combinations of Lewis acids and added bases for living polymerization. Among the many common Lewis acids for cationic polymerization, 10 we started with iron (III) halides (FeX3) because of their various advantages for industrial use: they are easy to handle, have low toxicity, and are economically efficient. 11 Several studies have been reported on the acidity of FeCl3 determined by various methods since the 1940s, and it is considered to be a strong acid. 12 In comparison with AlCl3 and SnCl4, for example, the acidity decreases in the order of AlCl3> FeCl3> SnCl4 according to the degree of interaction with a carbonyl group. 13 A different order, FeCl3> SnCl4> AlCl3, has been observed for the formation reaction of carbocations from a chloroalkane in the presence of a carbonyl compound. 14 Because of its strong acidity and smaller interaction with a carbonyl compound, FeCl3 is expected to induce fast living cationic polymerization with an added base, the rate of which would be even greater than that with SnCl4. Although there are several examples of cati-