Thermoresponsive Soft Actuator Using a Highly Accurate and Robust Liquid Crystalline Polyurethane Elastomer

Herein, the fabrication and thermal properties of liquid crystalline polyurethane (LCPU) elastomers are investigated to expand the application range of soft actuators. The synthesized materials exhibited reversible macroscopic deformation during heating and cooling cycles near human body temperature even without an external force applied, as well as long-term durability and a cyclic response over 47,000 times, with high accuracy and robustness to temperature change. Analytical results suggested that the cross-linked liquid crystal moieties of the LCPU elastomers were responsible for their shape memory behavior. Notably, a 3.4 kg fruit basket suspended by LCPU fibers was lifted when the fibers shrank upon heating. The remarkable macroscopic size change even under a heavy load suggests that the synthesized LCPU elastomers could be applied as soft actuators.