Exchangeable Liquid Crystal Elastomers With Ultra‐Stable Actuation Over 200 000 Cycles

Liquid crystal elastomers (LCEs) are among the most promising candidates for next‐generation soft actuators in robotics and wearable systems. Exchangeable LCEs (xLCEs) enable permanently crosslinked actuators with reprogrammable actuation modes. However, undesirable exchange reactions during thermal actuation can disrupt the orientation order of the liquid crystals, reducing device lifetimes and compromises reliability. Here, we synergistically integrate a reversible catalyst with the universal transesterification‐based xLCEs to achieve ultra‐stable actuation over 200 000 cycles—a 20‐fold improvement over the previous best xLCE. The catalyst reversibly transitions between active and inactive states in response to temperature, thereby suppressing transesterification at the actuation temperature while promoting it at the reprogramming temperature. At the actuation temperature, the xLCEs exhibit ultra‐stable actuation. Upon heating, efficient reprogramming is enabled. Upon cooling, the xLCE returns to its stable state. This strategy allows xLCEs to be repeatedly reprogrammed while maintaining ultra‐stable actuation performance. Moreover, it offers a general framework for designing both stable and reprogrammable shape‐morphing polymers by coupling high‐activation‐energy dynamic bonds with reversible catalysts.