Optical deformations of azobenzene polymers: Orientation approach vs. photofluidization concept
Optical deformations of azobenzene polymers: Orientation approach vs. photofluidization concept
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DOI：
10.1002/jsid.294
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发表时间：
2015-04
影响因子：
2.3
通讯作者：
M. Saphiannikova;V. Toshchevikov
中科院分区：
文献类型：
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作者：
M. Saphiannikova;V. Toshchevikov
最近在文献中出现了相当多的声称，偶氮苯（偶氮）发色团的环状异构化可能导致玻璃态偶氮聚合物或更一般地，玻璃态偶氮材料进入流体状态的非热转变。在这项研究中，我们对最近发表的研究结果进行了批判性的概述，并表明所提出的观察结果不仅不支持这种光流化概念，而且相反。玻璃态偶氮材料在光照下保持固态。因此，最近研究的标题中提出的合理主张与其文本中提出的实验观察相矛盾。此外，我们还讨论了一些严格的研究，提出了强有力的证据，反对光流化的概念，包括我们自己的理论预测的框架中的取向方法。这种方法提供了足够大的各向异性光致应力值，以使具有不同化学结构的玻璃态偶氮聚合物变形。应力值与最近的实验结果完全雅阁，实验结果表明吸附在发光偶氮聚合物顶部的金属和石墨烯多层膜中的键发生变形。
Recently in literature appeared quite a number of claims that cyclic isomerization of azobenzene (azo) chromophores may cause an athermal transition of the glassy azo‐polymers or, more generally, glassy azo‐materials into a fluid state. In this study, we provide a critical overview of recently published findings and show that observations presented not only fail to support this photofluidization concept but rather show the contrary. The glassy azo‐materials remain in the solid state under light illumination. Thus, the sound claims made in the titles of recent studies contradict the experimental observations presented in their texts. Further, we discuss a number of rigorous studies, which present strong evidence against the photofluidization concept, including our own theoretical predictions made in the frame of orientation approach. This approach provides values of anisotropic light‐induced stress large enough to deform glassy azo‐polymers with diverse chemical structures. The values of the stress are in a perfect accord with recent experimental findings, which show deformation of the bonds in metal and graphene multilayers adsorbed on the top of illuminated azo‐polymers.