Crack‐Resistant and Tissue‐Like Artificial Muscles with Low Temperature Activation and High Power Density

Abstract Constructing soft robotics with safe human–machine interactions requires low‐modulus, high‐power‐density artificial muscles that are sensitive to gentle stimuli. In addition, the ability to resist crack propagation during long‐term actuation cycles is essential for a long service life. Herein, a material design is proposed to combine all these desirable attributes in a single artificial muscle platform. The design involves the molecular engineering of a liquid crystalline network with crystallizable segments and an ethylene glycol flexible spacer. A high degree of crystallinity can be afforded by utilizing aza‐Michael chemistry to produce a low covalent crosslinking density, resulting in crack‐insensitivity with a high fracture energy of 33 720 J m −2 and a high fatigue threshold of 2250 J m −2 . Such crack‐resistant artificial muscle with tissue‐matched modulus of 0.7 MPa can generate a high power density of 450 W kg −1 at a low temperature of 40 °C. Notably, because of the presence of crystalline domains in the actuated state, no crack propagation is observed after 500 heating–cooling actuation cycles under a static load of 220 kPa. This study points to a pathway for the creation of artificial muscles merging seemingly disparate, but desirable properties, broadening their application potential in smart devices.