High-Strength, Large-Deformation, Dual Cross-Linking Network Liquid Crystal Elastomers Based on Quadruple Hydrogen Bonds.

Liquid crystal elastomers (LCEs) with large deformation under external stimuli have attracted extensive attention in various applications such as soft robotics, 4D printing, and biomedical devices. However, it is still a great challenge to reduce the damage to collimation and enhance the mechanical and actuation properties of LCEs simultaneously. Here, we construct a new method of a double cross-linking network structure to improve the mechanical properties of LCEs. The ureidopyrimidinone (UPy) group with quadruple hydrogen bonds was used as the physical cross-linking unit, and pentaerythritol tetra(3-mercaptopropionate) was used as the chemical cross-link. The LCEs showed a strong mechanical tensile strength of 8.5 MPa and excellent thermally induced deformation (50%). In addition, the introduction of quadruple hydrogen bonds endows self-healing ability to extend the service life of LCEs. This provides a generic strategy for the fabrication of high-strength LCEs, inspiring the development of actuators and artificial muscles.