School of Materials Science and Engineering, Tianjin Key Laboratory of Building Green Functional Materials, Tianjin Chengjian University, Tianjin, 300384, China.
The Synthetic Chemical & Engineering Institute of Inner Mongolia, Huhhot, 010010, China.
Macromol Rapid Commun. 2021 Apr;42(7):e2000704. doi: 10.1002/marc.202000704. Epub 2021 Jan 15.
As an intriguing characteristic of azobenzene-containing materials (azo-materials), photoinduced changes in mechanical properties (e.g., photosoftening) have stimulated many efforts both theoretically and experimentally. Here a simple yet powerful tool (i.e., a light-associated surface wrinkling-based method) to study the photosoftening effect in azobenzene-polymer (azo-polymer) supramolecular complexes is reported. The photo-induced modulus decrease of supramolecular complex films is deduced by analyzing the change of critical wrinkle wavelength of strain-induced surface wrinkling, in the case of varying experiment parameters. In particular, thanks to the facile modular tunability of the supramolecular system, the photosoftening effect has been systematically investigated as a function of azo-moiety content and the molecular weight of the host polymer. Notably, a photosoftening coefficient that is related to the chemical composition/structure of azo-polymers is introduced, and a simple formula that can quantify the connection of the photosoftening with external irradiation conditions and internal chemical factors of azo-polymers is derived for the first time. The obtained results are of great importance not only to enhance understanding of the photosoftening mechanism, but also to thoroughly apply it in diverse smart fields.
作为含偶氮苯材料（azo-materials）的一个有趣特性，机械性能的光致变化（例如光软化）在理论和实验上都激发了许多努力。在这里，报道了一种简单而强大的工具（即基于光相关表面皱缩的方法）来研究偶氮聚合物（azo-polymer）超分子复合物中的光软化效应。通过分析应变诱导表面皱缩的临界皱缩波长的变化，推导出超分子复合物膜的光致模量降低，在改变实验参数的情况下。特别是，由于超分子体系的易于模块化调谐性，系统地研究了光软化效应作为偶氮部分含量和主体聚合物分子量的函数。值得注意的是，引入了与偶氮聚合物的化学成分/结构有关的光软化系数，并首次推导出了一个可以量化光软化与外部辐照条件和偶氮聚合物内部化学因素之间联系的简单公式。所得到的结果不仅对增强对光软化机制的理解具有重要意义，而且对彻底应用于各种智能领域也具有重要意义。
