Enhanced Fatigue Resistance of Liquid Crystal Elastomers Enabled by Dynamic Sacrificial Bonds

Fatigue resistance and elasticity are critical factors in extending the service life of liquid crystal elastomers (LCEs) and expanding their application fields. Currently, most of the LCE-related studies focus on achieving large reversible deformations, while research on fatigue-resistant LCE material is relatively limited. Here, we report a facile strategy to improve the fatigue resistance of LCEs by introducing partial dynamic sacrificial bonds (tetraarylsuccinonitrile, TASN) into polymeric matrixes. It is found that increasing the amount of TASN units leads to a decrease in the LC-to-isotropic phase transition temperature, topology freezing transition temperature, and thermal actuation strain while concurrently resulting in an increase in elongation at break. Most notably, the LCE–TASN materials exhibit exceptional fatigue resistance, as evidenced by their ability to withstand 3000 cyclic stretching with a substantial 100% strain load, and they also demonstrate rapid self-recovery in as little as 5 min. This remarkable performance is attributed to the reversible dissociation and recombination of the dynamic central C–C bonds of the TASN units, a feature not found in conventional LCE materials. The current work provides insight into the design of fatigue-resistant LCEs, thereby helping to expand the application of LCEs.