Durable liquid-crystalline vitrimer actuators.

Vitrimer-based liquid-crystalline elastomers (LCEs) exhibit great advantages over the traditional LCEs due to their inherent processability to realize monodomain alignment and construction of LCE actuators with complex 3D structures in a robust way. Though exciting progress has been made, how to achieve a proper balance between processability and actuation durability/stability remains a big challenge. Here, we report a strategy to mitigate the conflict between processability and actuation stability by reducing the catalyst content in an epoxy/acid LCE vitrimer system. With a relatively low catalyst content (0.25 mol% to carboxyl group), monodomain LCEs with large actuation strain (∼95%) and excellent actuation stability (the actuation strain is completely maintained after 100 heating-cooling cycles and more than 90% of the initial strain is retained even after 500 cycles) could be easily prepared. Moreover, the monodomain LCEs can still be readily realigned or directly reconfigured into complex reversible 3D actuators.