MOF-Induced Pore Confinement: A Strategy for Thermomechanically Robust and High-Strength Liquid Crystal Elastomers.

Abstract

Liquid crystal elastomers (LCEs) are premier candidates for soft robotics due to their large, reversible actuation. However, their utility is often restricted by a fundamental trade-off: as temperature increases, orientational order diminishes, causing a sharp loss in load-bearing capacity and actuation stress above the isotropic transition. Here, we report a sequential integration strategy that overcomes this thermal limitation by embedding ultrathin Cu-TCPP metal-organic framework (MOF) nanosheets within the LCE network. This approach establishes a pore-confinement-enabled architecture that restricts segmental relaxation and preserves molecular alignment even under harsh thermal conditions. The resulting LCE-MOF composites exhibit exceptional mechanical robustness, achieving a tensile strength of 79 MPa at 25°C and maintaining 4.2 MPa at 200°C. Notably, the materials deliver a high actuation stress of 3.9 MPa at 200°C, significantly outperforming composites fabricated via conventional direct mixing. This confinement strategy effectively decouples mechanical integrity from thermal transitions, as demonstrated by a high-performance passive thermal valve capable of reliable switching in extreme environments. Our work provides a versatile methodology for designing resilient, high-output soft actuators for aerospace, industrial, and high-temperature hazardous applications where thermal stability and reliable actuation are critically demanded.