Azobenzene-containing Alternating and Random Metathesis Copolymers toward Gaining More Insight into Photoisomerization Properties
Azobenzene-containing Alternating and Random Metathesis Copolymers toward Gaining More Insight into Photoisomerization Properties
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DOI：
10.1021/acs.macromol.0c02621
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发表时间：
2021-09
期刊：
影响因子：
5.5
通讯作者：
Wei Song;Xiaotian Qu;Yadi Li;Juan Li;Chengshuang Wang;Liang Ding
中科院分区：
文献类型：
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作者：
Wei Song;Xiaotian Qu;Yadi Li;Juan Li;Chengshuang Wang;Liang Ding
采用交替二烯复分解（ALTMET）缩聚和无环二烯复分解（ADMET）聚合方法，由缺电子偶氮苯（偶氮）功能化的α，ω-二烯类光敏分子单体与富电子咔唑、芴功能化的二烯或二丙烯酸酯单体合成了两种交替无规共聚物。所有这些共聚物都是定制的，以探索交替和无规单体序列和电子转移能力对自组装形态和光响应性能的影响。正如预期的那样，在这些共聚物中的偶氮单元的独特的吸收特性，观察到在其光谱，这不能通过传统的含偶氮的均聚物和共聚物实现。由于共聚物中含有刚性的、富电子的咔唑或芴基序，两种单体的序列差异和共聚物链中的电子效应在一定程度上降低了光致异构化的能力和效率。此外，交替共聚物的尺寸和形态可以通过亚甲基间隔基和刚性共轭基序的序列进行调制，产生不同的纳米结构，导致不同的链移动性，最终表现出独特的光异构化行为。这些有趣的发现不仅证明了一种简单有效的方法来构建偶氮咔唑和偶氮芴易位共聚物，而且还扩展了含偶氮聚合物的光学性质。
Using alternating diene metathesis (ALTMET) polycondensation and acyclic diene metathesis (ADMET) polymerization, two kinds of alternating and random copolymers from electron-deficient azobenzene (azo)-functionalized α,ω-diene monomers that are photoresponsive molecules and comonomers such as electron-rich carbazole or fluorene-functionalized diene or diacrylate monomers were synthesized. All of these copolymers were tailored to explore the effects of alternating and random monomer sequences and electron transfer capability on the self-assembly morphology and photoresponsive properties. As expected, the distinct absorption features from azo units in these copolymers are observed in their optical spectra, which cannot be achieved by traditional azo-containing homo- and copolymers. Because of the presence of stiff and electron-rich carbazole or fluorene motifs, the ability and efficiency of photoisomerization was depressed to some extent according to the sequential differences of two monomers and the electron effect in the copolymer chain. Moreover, the sizes and morphologies of alternating copolymers can be modulated through the methylene spacer and sequence of rigid conjugated motifs generating diverse nanostructures leading to a different chain mobility, which ultimately exhibited the unique photoisomerization behaviors. These interesting findings not only demonstrate a facile and efficient method for constructing azo-carbazole and azo-fluorene metathesis copolymers but also expand the optical properties of azo-containing polymers.