Enhancing Mechanical Properties in Polyurethane Liquid Crystal Elastomer Actuators Responsive to Light, Heat, and Humidity

Liquid crystal elastomers (LCEs) represent an exclusive category of smart materials that produce prominent bulk shape changes triggered by diverse environmental stimuli. Integrating multistimulus responses and excellent mechanical toughness into monolithic LCEs can substantially expand their practical potential for complicated surroundings. Herein, we report a multistimulus-responsive chemically cross-linked polyurethane liquid crystal elastomer (PULCE) structure with excellent comprehensive performance and mechanical toughness. The actuator exhibits rapid photoinduced deformations upon exposure to unpolarized UV light at room temperature. Meanwhile, the actuator achieves diverse humidity-sensitive actuating motions, such as overturning on moist filter paper and curvature variation induced by human-palm moisture. Furthermore, the actuator achieves a large contraction strain at the phase transition temperature. In addition, the actuator possesses excellent mechanical properties and antipuncture ability. This integrated strategy that combines multistimulus responses (light, humidity, and heat) with excellent mechanical properties opens up a path for the tailored design and exploitation of multistimuli-sensitive soft robots.