Mechanically Robust Photo-responsive Liquid Crystal Elastomers

Photoresponsive liquid crystal elastomers (LCEs) are promising for applications in soft robotics and smart devices owing to their precise controllability and excellent stability. However, their practical utility is often hampered by limitations such as notably inferior mechanical properties, a single shape memory effect, and inadequate recyclability. To address these challenges, we developed a photoresponsive liquid crystal-polyurethane interpenetrating polymer network (IPN-0.75) that exhibits outstanding mechanical performance, including an ultrahigh tensile stress of 44 MPa and a fracture strain of 1699%. The material also demonstrated excellent recyclability, retaining 93% of its original tensile strength after five recycling cycles. Moreover, IPN-0.75 shows remarkable photostability with a consistent response time (∼8 s) and a maximum bending angle (∼85°) over 10 actuation cycles. By integration of a triple shape memory effect and overcoming the mechanical weaknesses of conventional LCEs, this work opens up new possibilities for advanced applications in adaptive and sustainable soft actuators.