Readily Programmable, Body Temperature-Responsive Liquid Crystal Elastomers With Dynamic Covalent Thiourea Bonds

Liquid crystal elastomers (LCEs) are promising stimuli-responsive materials for applications in wearable devices, biomedical devices, and soft robotics owing to their thermotropic shape-changing behaviors. However, conventional LCEs exhibit high phase-transition temperatures, often exceeding 60°C, which limits their use in human-interfacing applications. Herein, we present body heat-responsive LCEs incorporating dynamic thiourea bonds. Body temperature actuation is achieved by introducing comonomers that weaken anisotropic intermolecular interactions among mesogens into these LCEs, while the dynamic thiourea bonds impart reprocessability to the cross-linked network. Systematic formulation study elucidates the influence of comonomer structure on the actuation performance and network malleability. Furthermore, the dynamic thiourea-based LCE demonstrates reprogrammability even at ambient temperature, enabling facile fabrication of mechanically programmed 3D structures. Finally, we showcase a bump-array actuator that reversibly changes its surface topography in response to body heat.