Photoswitching of glass transition temperatures of azobenzene-containing polymers induces reversible solid-to-liquid transitions
Photoswitching of glass transition temperatures of azobenzene-containing polymers induces reversible solid-to-liquid transitions
复制标题
DOI：
10.1038/nchem.2625
复制
发表时间：
2017-02-01
期刊：
影响因子：
21.8
通讯作者：
Wu, Si
中科院分区：
文献类型：
--
作者：
Zhou, Hongwei;Xue, Changguo;Wu, Si
具有可切换玻璃化转变温度（$T_g$）的聚合物的开发能够解决一些科学难题，比如高$T_g$聚合物中裂纹的修复以及在不使用增塑溶剂的情况下在室温下加工硬质聚合物。在此，我们证明了光能够切换含偶氮苯的聚合物（偶氮聚合物）的$T_g$，并诱导聚合物发生可逆的固 - 液转变。聚合物中的偶氮苯基团具有可逆的顺 - 反光异构化能力。反式偶氮聚合物是$T_g$高于室温的固体，而顺式偶氮聚合物是$T_g$低于室温的液体。由于这些聚合物的光诱导固 - 液转变，光能够使偶氮聚合物薄膜的表面粗糙度降低近600%，反复修复偶氮聚合物中的裂纹，并控制偶氮聚合物用于转印的粘附性。$T_g$的光控切换为设计具有高$T_g$的可修复聚合物提供了一种新策略，并能够以高时空分辨率控制聚合物的机械性能。
The development of polymers with switchable glass transition temperatures (T-g) can address scientific challenges such as the healing of cracks in high-T-g polymers and the processing of hard polymers at room temperature without using plasticizing solvents. Here, we demonstrate that light can switch the T-g of azobenzene-containing polymers (azopolymers) and induce reversible solid-to-liquid transitions of the polymers. The azobenzene groups in the polymers exhibit reversible cis-trans photoisomerization abilities. Trans azopolymers are solids with T-g above room temperature, whereas cis azopolymers are liquids with T-g below room temperature. Because of the photoinduced solid-to-liquid transitions of these polymers, light can reduce the surface roughness of azopolymer films by almost 600%, repeatedly heal cracks in azopolymers, and control the adhesion of azopolymers for transfer printing. The photoswitching of T-g provides a new strategy for designing healable polymers with high T-g and allows for control over the mechanical properties of polymers with high spatiotemporal resolution.