Liquid Crystalline Elastomers with Tailorable Actuation Performance Based on Orthogonal Click Chemistries

Abstract

Liquid crystalline elastomers (LCEs) are excellent candidates for actuators and soft robotics owing to their exceptional properties. Their actuation relies on the precise control of the liquid crystalline orientation within the elastomeric network during synthesis. Current two-stage synthesis methods, which involve consecutive thiol-acrylate addition (or amine-acrylate addition), mechanical stretching, and free-radical polymerization of residual acrylate, typically suffer from extended reaction times and oxygen inhibition caused by the homopolymerization of acrylate. Here, we present a systematic examination of LCEs based on thiol click chemistries and introduce a novel approach to the design of LCEs using orthogonal radical-mediated thiol-ene and base-catalyzed thiol-epoxy click chemistries. This newly developed one-pot, two-stage strategy overcomes the limitations associated with acrylate-based chemistry. By changing the sequence and relative ratio of the click reactions, we successfully prepare LCEs with tailorable thermal properties and actuation performance, providing enhanced design flexibility compared with the conventional LCE chemistries. Using this strategy, we demonstrate the preparation of LCE actuators capable of showing intricate and reversible shape changes. This study highlights the use of orthogonal click chemistries as an efficient approach to the design and fabrication of LCEs.