Leibniz-Institut für Polymerforschung, Hohe Str. 6, 01069 Dresden, Germany.
Soft Matter. 2017 Apr 12;13(15):2823-2835. doi: 10.1039/c7sm00115k.
Azobenzene-containing smart materials are able to transform the energy of light into directional mechanical stress. We develop a theory of time-dependent light-induced ordering and deformation in azobenzene materials starting from the kinetic equations of photoisomerization. The liquid crystalline (LC) interactions between rod-like trans-isomers are taken into account. Angular selectivity of the photoisomerization known as an "angular hole burning" or the Weigert effect leads to the light-induced ordering and deformation of the azobenzene materials. The time evolution of ordering and deformation is found as a function of intensity of light depending on the opto-mechanical characteristics of the materials, such as probabilities of the optical excitation of trans- and cis-isomers, angular jump during the single isomerization event, viscosity of the materials, strength of the LC interactions in both the isotropic and LC materials, and the angular distribution of chromophores in polymer chains. Established structural-property relationships are in agreement with a number of experiments and can be used for the construction of light-controllable smart materials for practical applications.
含偶氮苯的智能材料能够将光能转化为定向机械应力。我们从光致异构化的动力学方程出发，为偶氮苯材料中的时变光诱导有序和变形开发了一种理论。棒状反式异构体之间的液晶（LC）相互作用被考虑在内。光致异构化的角选择性，即所谓的“角孔烧蚀”或魏格特效应，导致偶氮苯材料的光诱导有序和变形。有序和变形的时间演化被发现是光强的函数，这取决于材料的光电机械特性，如反式和顺式异构体的光激发概率、单异构化事件期间的角跳跃、材料的粘度、各向同性和 LC 材料中 LC 相互作用的强度，以及聚合物链中发色团的角分布。已建立的结构-性能关系与许多实验一致，可用于构建用于实际应用的光可控智能材料。
