An Amino-Yne Click Chemistry Approach for Multi-Responsive Liquid Crystal Elastomer Actuators.

The spontaneous amino-yne click reaction is introduced for the first time as a fast, efficient, and ambient temperature strategy for preparing multi-responsive Liquid Crystal Elastomer (LCE) actuators. This synthetic approach relies on the amino-yne cross-linking between secondary amines along the main chain of poly(β-amino ester) liquid crystal oligomers and a dipropiolate-functionalized cross-linker, rendering β-aminoacrylate cross-linking points. After alignment and locking via dynamic transesterification at 30 °C, the resulting LCE actuators exhibit reversible and reproducible thermal and light-induced actuation. The generated tension and activation kinetics are easily tunable by adjusting the cross-linker content. Additionally, leveraging the acid-triggered reactivity of the network enables it to respond to additional stimuli, including water-driven actuation. By integrating the capability for dynamic bond exchange, this LCE formulation opens new avenues for designing structures with complex molecular orientation patterns. As a proof of concept, a star-shaped soft actuator is fabricated, demonstrating diverse programmable actuation modes.