Intrinsically Luminescent, Reprogrammable, and Chemically Recyclable Liquid Crystal Elastomers Enabled by Dynamic...

Liquid crystal elastomers (LCEs) with integrated functionalities are critical for developing advanced soft actuators. However, challenges remain in simultaneously achieving reprogrammability, chemical recyclability, and intrinsic luminescence within existing exchangeable LCE systems. Herein, we develop a new class of LCE based on dynamic vinylogous urethane (VU) bonds to address these challenges, where VU moieties serve as both crosslinking points and luminescent clusters. The optimal polydomain vinylogous urethane-based LCE (VULCE) material exhibits excellent mechanical properties, with a Young's modulus of 1.45 ± 0.08 MPa and a toughness of 148.26 ± 0.11 KJ m^-3. Thanks to the catalyst-free transamination of VU bonds, the VULCE enables reprogramming into diverse three dimensional (3D) actuators with reversible actuation at 110°C for 10 min. Furthermore, the VULCE network can be depolymerized into LC oligomers and small molecules in an organic solvent under excess bifunctional amines at 80°C for 6 h. The recycled solution can be repolymerized into new VULCE with arbitrary shapes by reintroducing chain extenders, mesogenic monomers, and crosslinkers, achieving polymer-oligomer/small molecule-polymer recycling. More importantly, the VULCE emits intrinsic blue fluorescence owing to the clustering-triggered emission (CTE) effect. This work demonstrates unprecedented multifunctionality, providing new insights for the development of multifunctional integrated LCE materials.