Title: Three-dimensional liquid crystal polymer actuators assembled by athermal photo-welding

Author: Yaoqing Feng, Jia Wei, Lang Qin*, Yanlei Yu*

Journal: Soft Matter, 2023, 19, 999-1007

Abstract:

Photodeformable liquid crystal polymers (LCPs) exhibit shape changes of different modes like bending, twisting, and oscillation, which depend on the orientation of liquid crystals. However, it is challenging to create a three-dimensional (3D) actuator with distinct actuation modes due to the difficulty of local orientation in a complex bulk architecture. Here we propose a strategy based on athermal photo-welding to integrate different orientations into a single flexible actuator by the photofluidization of azobenzene-containing linear LCPs. Stretch-induced uniaxial films are cut in different directions and subsequently welded via local photofluidization, during which the LCP transitions from a high-modulus glassy state to a rubbery state upon photoisomerization of azobenzene at room temperature. As a consequence, a cucumber vine-like structure with the opposite handedness and a lifting gripper are constructed by such a cut-and-weld process, demonstrating diverse deformation modes of winding, unwinding, and curling. This strategy provides an athermal process for the fabrication of seamless 3D flexible actuators without structural defects, which have potential applications in micromechanical systems, soft robotics, and artificial muscles.

论文链接：https://pubs.rsc.org/en/content/articlelanding/2023/sm/d2sm01476a

PDF下载：Three-dimensional liquid crystal polymer actuators assembled by athermal photo-welding.pdf

在本工作中，我们采用开环易位聚合（ROMP）的方法合成了一系列具有不同侧链结构的液晶聚合物。并且，利用光焊接以及切割工艺制备了具有不同液晶基元取向的3D复合执行器。无热光焊接的实现来源于含有偶氮苯基团的液晶聚合物的光致流体化现象，该现象是由于室温下偶氮苯基团的光致异构化使得液晶聚合物从高模量的玻璃态转变为橡胶态。基于该原理，在光照下，我们将具有不同取向的液晶聚合物条带利用光焊接制备成具有相反螺旋方向的黄瓜藤状结构以及一种提拉夹具。本文报道的这种光焊接方法可以应用于任何表现出光致流体化的聚合物，而且它还能够在保证焊接区域内不存在结构缺陷的情况下集成不同材料。