Thermoplastic Liquid Crystal Elastomers Based on ABA-type Triblock Copolymers

Liquid crystal elastomers (LCEs) are compelling smart materials for soft robotics and flexible electronics. However, both conventional and dynamically crosslinked LCE systems fundamentally rely on chemically crosslinked networks, which has long been regarded as a prerequisite for their reversible actuation. While thermoplastic elastomers based on block copolymers offer a structural model for constructing robust physically crosslinked networks, it remains a significant challenge to transplant this design strategy into LCEs to realize reversible actuation in non-co-valently crosslinked system. Herein, we develop a physically crosslinked thermoplastic LCE system based on ABA-type triblock copolymers (PS- b -MCLCP- b -PS). Polystyrene (PS) hard-block aggregates act as reversible physical crosslinking sites, effectively replacing permanent covalent bonds. We systematically investigated the regulatory effect of the PS block content on the microstructure, mechanical properties, and thermally responsive actuation of the materials. By achieving an optimal balance between physical network confinement and the segment mobility of the liquid crystal phase, the resultant elastomer exhibits excellent reversible thermally driven actuation, well-balanced mechanical properties and solvent recyclability with high mechanical retention. Furthermore, the material demonstrates prominent wide-temperature-range damping performance attributed to the synergistic energy dissipation of the physical network and mesogen rotation. This work offers a feasible molecular design strategy for sustainable and multifunctional LCEs to break the dependence on chemical crosslinking for reversible actuation.