Photoinduced orientation and cooperative motion of three epoxy-based azo polymers
Photoinduced orientation and cooperative motion of three epoxy-based azo polymers
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DOI：
10.1007/s00289-011-0694-6
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发表时间：
2012-04
期刊：
影响因子：
3.2
通讯作者：
Yanwei Wang;Yaning He;Xiaogong Wang
中科院分区：
文献类型：
--
作者：
Yanwei Wang;Yaning He;Xiaogong Wang
本文研究了三种含不同类型偶氮生色团的环氧基聚合物的光诱导取向。以双酚A二缩水甘油醚和苯胺为原料，通过分步聚合反应合成了环氧基前体聚合物（BP-AN），并通过后聚合偶氮反应合成了环氧基偶氮聚合物。通过双折射表征、偏振红外光谱和二维红外相关光谱（COS）研究了发色团的取向和主链基团的协同运动。结果表明，环氧基偶氮聚合物的取向行为与偶氮发色团上的吸电子基团密切相关。偶氮聚合物BP-AZ-CN，其中包含偶氮生色团与氰基作为吸电子基团，显示出最快的双折射增长率。含羧基吸电子基团的偶氮聚合物BP-AZ-CA具有较高的双折射残余值和最高的饱和取向度。偏振FTIR和2D-IR COS揭示了偶氮苯结构与非光致变色聚合物主链之间的协同运动。光致各向异性是偶氮发色团和聚合物主链取向的结果。对结构-性能关系的理解可以用于开发具有更好性能的材料，用于数据存储和其他应用。
In this work, photoinduced orientation of three epoxy-based polymers bearing different type azo chromophores was studied. The epoxy-based azo polymers were synthesized through post-polymerization azo-coupling reactions based on an epoxy-based precursor polymer (BP-AN), which was synthesized by the step polymerization between bisphenol-A diglycidyl ether and aniline. The chromophore orientation and cooperative motion of the main-chain groups were studied by birefringence characterization, polarized infrared spectroscopy, and two-dimensional (2D)-IR correlation spectroscopy (COS). The results show that the orientation behavior of the epoxy-based azo polymers is closely related with the electron-withdrawing groups on the azo chromophores. The azo polymer BP-AZ-CN, which contains azo chromophores with cyano as the electron-withdrawing group, shows the fastest birefringence growth rate. The azo polymer BP-AZ-CA, containing carboxyl as the electron-withdrawing group, possesses high birefringence residual value and the highest saturated orientation degree in the series. Cooperative motion between azobenzene moieties and non-photochromic polymer backbone was revealed by polarized FTIR and 2D-IR COS. The photoinduced anisotropy is a result of the orientation of both azo chromophore and polymer main-chain. The understanding of the structure–property relationships can be used to develop materials with better performance for data storage and other applications.