光/溶剂诱导液晶基柔性驱动器自振荡运动的机制及应用研究

Soft actuator has the capability to convert environmental stimuli into mechanical motions, which has a broad application prospect in bionics, energy conversion and other fields. However, it is very difficult to guide the deformation direction and to achieve continuous motion driven by a constant stimulus. In this project, we will propose to use the molecular design strategy of continuous dynamic change of soft actuator caused by “continuous isomerization” or “continuous adsorption and desorption of solvent” to prepare the deformation controllable soft actuator, realizing the continuous motion under constant stimulation. The liquid crystal based soft actuator with self-oscillation property will be used for bionics and power generation. The single-layer and oriented azobenzene liquid crystal will be prepared by photopolymerization, and the mechanical motion characteristics under external stimulation will be investigated. Furthermore, we will focus on studying the design strategy of the self-oscillating soft actuator, the stimulation response mechanism, and the micro process between energy conversion and mechanical motion. Therefore, the results of this project will not only promote the development of self-oscillating actuators, but also deepen the understanding of basic scientific issues such as energy conversion mechanism in micro process.

柔性驱动器可将外部能量直接转化为机械形变，在动植物仿生、能量转化等领域有着广阔的应用前景。然而目前柔性驱动器存在形变难以调控且不可持续运动等问题。本项目拟利用“不停发生的光顺反异构”、“溶剂不停的吸附与解析”导致柔性驱动器持续不停的动态变化这一分子设计策略，制备形变可控的液晶基柔性驱动器，并在恒定刺激下实现持续运动的自振荡行为，优化其在仿生、发电领域的应用。拟合成易溶于挥发性有机溶剂的光响应型偶氮苯液晶单体，采用光聚合方法制备单层、取向的液晶基柔性驱动器。结合外界刺激下的机械运动特性，阐明自振荡柔性驱动器的分子设计策略和液晶取向调控形变方向的机理，揭示自振荡的运动机制与微观过程。本项目的成功实施不但有利于自振荡柔性驱动器智能材料的发展，还将有助于深化微观过程中能量转化机制等基础科学问题的认识。

液晶基柔性驱动器可以在外界刺激的作用下产生形变或运动，并且具有轻质、低能耗的机械性能等优势，从而有望用于人工肌肉、可穿戴设备以及软体机器人等高新技术领域。然而目前柔性驱动器存在形变难以调控且不可持续运动等问题。为了克服上述难题，本项目通过偶氮苯分子的光响应性和“溶剂不停的吸附与解析”这一设计策略，合成同时具备光响应并易溶于挥发性有机溶剂的偶氮苯类液晶单体AZO，制备形变可控的液晶基柔性驱动器，实现持续不停的动态变化。负责人制备出形变可控（形变方向垂直取向方向）和能在二氯甲烷刺激下实现自振荡运动的柔性驱动器。根据不同的裁减方向，使得液晶膜的长轴方形和取向方向呈现不同的角度，在二氯甲烷溶剂直接接触的刺激下成功实现了定向的形状变化。在与二氯甲烷非接触的弯曲过程中，薄膜底面和顶面之间的二氯甲烷溶剂浓度梯度导致两侧膜的不对称膨胀，在薄膜重力和与基底摩擦的共同作用下，柔性驱动器发生自振荡运动。此外，杂化取向膜可以在405纳米波长的光照下实现定向的形变。本研究明确了液晶单体分子设计策略、柔性驱动器响应性能的优化条件和液晶取向调控形变方向的机理，揭示了溶剂刺激下的自振荡运动机制与微观过程。利用二氯甲烷溶剂和光的刺激响应，将薄膜材料巧妙地用于模仿自然界的生命现象，如随风摇摆的花草、爬行的虫子等，在仿生材料领域有着广阔的应用前景。