Dynamic Liquid Crystalline Networks for Twisted Fiber and Spring Actuators Capable of Fast Light-Driven Movement with Enhanced Environment Adaptability

Abstract

Carbon nanotube-loaded liquid crystalline Diels–Alder networks (CNT-LCDANs) were prepared and utilized to investigate twisted fiber and spring actuators for light-driven rolling movement. The twisted fiber actuator was obtained by inserting twists into uniaxially stretched thin rods, while the spring actuator was built up by coiling the twisted fiber with either the same or opposite handedness, giving rise to a homochiral and heterochiral spring actuator, respectively. The programming of such hierarchically twisted geometries of liquid crystalline polymer networks was enabled by the easy processing and the concomitant stabilization of LC alignment of CNT-LCDAN due to the dynamic, thermally reversible DA-bonded cross-links. High-performance, environment-adaptable rolling motion powered by constant exposure to light was achieved with the twisted fiber and spring actuators. The appealing characteristics include ultrafast motion speed (reaching 22 mm s–1), multiterrain locomotion (including sand, water, and human hand), movement under near-infrared (NIR) or visible light or even natural sunlight (on dark gray or black paper), and squeezing through narrowed opening through in-motion reversible body compression and extension. The material of CNT-LCDAN and its twisted fiber and spring actuators hold promise in the development of next-generation soft robotics.