A Closed-Loop-Recyclable Liquid-Crystalline Dynamic Covalent Network Soft Actuator Derived From Nonliquid-Crystalline Monomers

Liquid-crystalline networks constructed from nonliquid-crystalline precursors offer an alternative to conventional routes based on liquid-crystalline monomers, that is, mesogenic monomers. Here, we report a closed-loop recyclable liquid crystal polymer network (CLLCP) synthesized from nonliquid-crystalline aldehyde and amine building blocks through reversible imine chemistry. Imine formation constructs mesogenic segments and establishes network connectivity, linking liquid-crystalline structural design with chemical recyclability. This approach avoids pre-synthesis of liquid-crystalline monomers and offers flexibility in the selection of network components. The combination of rigid imine-linked segments and flexible spacers supports liquid-crystalline order and segmental mobility, while dynamic imine bonds enable stress relaxation and thermal reprocessing. Aligned CLLCP films exhibit a reversible thermomechanical actuation strain of 26% with good cycling stability. Under acidic conditions, imine hydrolysis disassembles the network and enables recovery of the four original molecular building blocks. These components are reused to reconstruct networks with phase behavior, mechanical properties, and actuation performance comparable to those of the pristine materials. This molecular design couples in situ mesogenic-segment construction with polymer-to-monomer closed-loop recycling, providing a modular route to sustainable liquid-crystalline soft actuators.