Xu Wen-Cong, Sun Shaodong, Wu Si
CAS Key Laboratory of Soft Matter Chemistry, Hefei National Laboratory for Physical Sciences at the Microscale, Anhui Key Laboratory of Optoelectronic Science and Technology, Department of Polymer Science and Engineering, University of Science and Technology of China, Jinzhai Road 96, Hefei, 230026, China.
Angew Chem Int Ed Engl. 2019 Jul 15;58(29):9712-9740. doi: 10.1002/anie.201814441. Epub 2019 Jun 18.
Heating and cooling can induce reversible solid-to-liquid transitions of matter. In contrast, athermal photochemical processes can induce reversible solid-to-liquid transitions of some newly developed azobenzene compounds. Azobenzene is photoswitchable. UV light induces trans-to-cis isomerization; visible light or heat induces cis-to-trans isomerization. Trans and cis isomers usually have different melting points (T ) or glass transition temperatures (T ). If T or T of an azobenzene compound in trans and cis forms are above and below room temperature, respectively, light may induce reversible solid-to-liquid transitions. In this Review, we introduce azobenzene compounds that exhibit photoinduced reversible solid-to-liquid transitions, discuss the mechanisms and design principles, and show their potential applications in healable coatings, adhesives, transfer printing, lithography, actuators, fuels, and gas separation. Finally, we discuss remaining challenges in this field.
加热和冷却能够引发物质从固态到液态的可逆转变。相比之下，非热光化学过程能够使一些新开发的偶氮苯化合物发生从固态到液态的可逆转变。偶氮苯具有光开关特性。紫外光会引发反式到顺式的异构化；可见光或热会引发顺式到反式的异构化。反式和顺式异构体通常具有不同的熔点（Tm）或玻璃化转变温度（Tg）。如果一种偶氮苯化合物的反式和顺式形式的Tm或Tg分别高于和低于室温，那么光可能会引发可逆的固态到液态的转变。在本综述中，我们介绍了表现出光致可逆固态到液态转变的偶氮苯化合物，讨论了其机理和设计原则，并展示了它们在可自愈涂层、粘合剂、转移印刷、光刻、致动器、燃料和气体分离等方面的潜在应用。最后，我们讨论了该领域仍然存在的挑战。
