Tough and High-Force-Output Liquid Crystal Elastomers as Soft Artificial Muscles for Macroscopic Mechanical Work

Liquid crystal elastomers (LCEs) are regarded as promising artificial muscles with potential applications in rehabilitation therapy, robotic systems, and other fields owing to their excellent stimulus responsiveness. However, most studies have focused on the deformation behavior or conventional mechanical properties of LCEs for developing soft devices, with relatively little attention paid to their actuation capabilities. If LCEs can stably generate actuation forces during stimulus-response processes in macroscopic applications, they could serve as potential alternatives to motors in driving mechanical systems, thereby advancing the development of LCE-based technologies. Here, we report tough and high-force-output liquid crystal elastomers (THFO-LCE) constructed through an interpenetrating network of polyurethane oligomer and LCE matrices. The THFO-LCE exhibits exceptional toughness, capable of supporting up to 1.09 × 10⁴ times its own weight. The THFO-LCE sample with a cross-sectional area of 6.37 mm² generates an actuation force of 7.8 N. Its actuation stress (1.2 MPa) remains nearly constant over a cross-sectional area range of 0.33–6.37 mm². Furthermore, the THFO-LCEs can propel a model car forward, demonstrating their potential to replace electric motors and highlighting their broad applicability for flexible actuation systems and next-generation soft robotics.