Electroactive Liquid Crystal Elastomers as Soft Actuators

Abstract Liquid crystal elastomers (LCEs) combine the anisotropic properties of liquid crystals (LC) and elastic properties of elastomers. LCEs present outstanding thermotropic properties including large and reversible skeletal‐muscle‐like strain, tunable processability, and high programmability. LCEs are extensively studied and increasingly considered as one of the competitive smart soft materials. Most LCEs use heat or light as external stimulus, where the temperature variation or light illumination disrupts the LC order and further the anisotropy of LC polymer chain conformation to eventually get material actuation. However, besides heat and light, electrical energy is the most convenient and the most in demand stimulus in actuators. This review discusses all kinds of electroactive LCEs (eLCEs) reported in literature with the emphasis on their chemical structures, their alignment methods to get monodomain sample, the design of conducting materials and electrodes, their actuation mechanism and performance, which will be helpful for the future development of eLCEs. This review discusses eLCEs actuated by electromechanical, electrochemical, and electrothermal mechanisms. Among these, only electrothermal eLCEs involve intrinsic thermo‐responsive expansion and contraction, which are induced by Joule heating through electronic and ionic conductive media incorporated into the LCEs. By contrast, electromechanical and electrochemical eLCEs operate as athermal electroactive systems.