The strain generated by photoresponsive polymer actuators under external applied loads is a key performance parameter. Herein, we investigated the photogenerated strain under uniaxial loads in densely crosslinked azobenzene-incorporated liquid crystalline polymer (azo-LCP) actuators. Spectral analysis indicated that the liquid crystalline (LC) moieties and incorporated azobenzene moieties behave independently under load. The degree of LC mesogen distortions decreased as the applied load increased, whereas azobenzene isomerization showed high tolerance towards the external load. Such stress-response differences led to universal “two-stage” photogenerated strain behavior, with rapid decreases under low applied loads and steady linear decreases under relatively high loads. More importantly, we found that light intensity has little influence on important parameters such as the loading stage and actuator failure stress. However, these properties could be optimized by changing the crosslinking density (either azobenzene or side-chain LC concentration) in the polymeric network.

在外部施加的负载下，光敏聚合物致动器产生的应变是关键的性能参数。在本文中，我们研究了在紧密交联的偶氮苯结合液晶聚合物（azo-LCP）致动器中单轴载荷下的光生应变。光谱分析表明液晶（LC）部分和结合的偶氮苯部分在负载下独立地表现。LC液晶元畸变的程度随施加的载荷增加而降低，而偶氮苯异构化显示出对外部载荷的高耐受性。这种应力-响应差异导致普遍的“两阶段”光生应变行为，在低施加载荷下迅速下降，而在相对高载荷下稳定地线性下降。更重要的是，我们发现光强度对重要参数的影响很小，例如加载阶段和执行器故障应力。但是，可以通过更改聚合物网络中的交联密度（偶氮苯或侧链LC浓度）来优化这些性能。