Photosensitive copolymers with various types of azobenzene side groups synthesized by living cationic polymerization
Photosensitive copolymers with various types of azobenzene side groups synthesized by living cationic polymerization
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DOI：
10.1002/pola.20892
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发表时间：
2005-09
期刊：
影响因子：
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通讯作者：
Tomohide Yoshida;S. Kanaoka;S. Aoshima
中科院分区：
文献类型：
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作者：
Tomohide Yoshida;S. Kanaoka;S. Aoshima
定义明确的光响应共聚物目前已引起人们的兴趣，因为它们的广泛的潜在应用，从生物相关的光开关系统，以环境友好的刺激响应材料。事实上，已经开发了各种类型的光致变色共聚物，例如偶氮苯、1二芳基乙烯、2和螺吡喃衍生物。3然而，在选定位置具有光响应部分的精确设计的乙烯基型共聚物很少有报道。4在光致变色基团中，偶氮苯是最知名的和最有用的光响应分子，具有许多潜在的应用。我们最近报道了第一个用含偶氮的乙烯基醚{4-[2-（乙烯氧基）乙氧基]偶氮苯（AzoVE）}与各种刘易斯酸在外加碱存在下进行活性阳离子聚合的实例。5尽管存在碱性氮原子，阳离子聚合仍以活性方式定量进行。产物聚合物溶液在特定波长的照射下发生偶氮基团的顺反异构化引发的光响应相分离。在不同波长下具有这种类型的光响应的聚合物可以通过改变与偶氮基团相邻的苯环的电子状态来实现。例如，为此目的，氨基、硝基或萘基可以连接到苯环上。因此，在这项研究中，研究了通过活性阳离子聚合合成具有各种偶氮型官能团的定义明确的光响应共聚物。然而，AzoVE及其衍生物的均聚物在普通有机溶剂中显示出相对差的溶解性，因此偶氮单体的共聚物应该与具有良好聚合物溶解性的另一种乙烯基醚合成。由于含偶氮乙烯基醚的统计共聚迄今尚未研究，我们研究了四种不同偶氮型乙烯基醚（图1）与异丁基乙烯基醚（IBVE）和Et 1的活性阳离子共聚。5AlCl 1。5在添加的碱的存在下。然后考察了共聚物在己烷中的光响应行为，重点考察了选择波长光敏性。
Well-defined photoresponsive copolymers have currently been eliciting interest because of their wide range of potential applications, from biorelated photoswitching systems to environmentally benign stimuliresponsive materials. In fact, various types of photochromic copolymers have been developed, such as azobenzene, 1 diarylethene, 2 and spiropyran derivatives. 3 However, precisely designed vinyl-type copolymers with a photoresponsive part at a selected position have rarely been reported. 4 Among photochromic groups, azobenzenes are the best known and most useful photoresponsive molecule for a number of potential applications. We have recently reported the first example of living cationic polymerization with an azo-containing vinyl ether {4-[2-(vinyloxy) ethoxy] azobenzene (AzoVE)} achieved with various Lewis acids in the presence of an added base. 5 The cationic polymerization proceeded quantitatively in a living fashion despite the presence of basic nitrogen atoms. The product polymer solution underwent photoresponsive phase separation triggered by the cis–trans isomerization of the azo groups under irradiation at a specific wavelength. Polymers with this type of photoresponse at different wavelengths can conceivably be realized by changes in the electronic states of the phenyl rings adjacent to the azo group. For example, an amino, nitro, or naphthyl group can be attached to the phenyl rings for this purpose. 6, 7 In this study, therefore, the synthesis of welldefined photoresponsive copolymers with various azotype functions via living cationic polymerization was examined. However, homopolymers of AzoVE and their derivatives show relatively poor solubility in common organic solvents, and as such copolymers of azo monomers should be synthesized with another vinyl ether with good polymer solubility. As the statistical copolymerization of an azo-containing vinyl ether has not been investigated to date, we examined the living cationic copolymerization of four different azotype vinyl ethers (Chart 1) with isobutyl vinyl ether (IBVE) with Et1. 5AlCl1. 5 in the presence of an added base. The photoresponsive behavior of the product copolymers in hexane was then examined, with the focus on the selective-wavelength photosensitivity.