Mesogen-Mimetic Anisotropic Crosslinkers for Load-Bearing Liquid Crystal Elastomer Artificial Muscles

Liquid crystal elastomers (LCEs) can generate large reversible contractions, but their practical work output is often limited by thermal softening and insufficient load-bearing capability at actuation temperatures. Here, we introduce PBB-TT as a mesogen-mimetic anisotropic tetrathiol crosslinker for molecularly reinforced LCE actuators. Unlike conventional flexible or non-rod-like crosslinkers that mainly provide isotropic molecular connectivity, PBB-TT incorporates a phenylene bisbenzoate-based anisotropic rigid core into a covalent LCE network. Although PBB-TT itself does not exhibit an independent liquid-crystalline phase, its liquid-crystal-compatible rigid core, tetrafunctional thiol connectivity, and flexible thioether/ether spacers enable it to function as an anisotropic reinforcing junction that improves high-temperature elastic stress support while retaining monodomain alignment for thermal actuation. The optimized PBB-LCE-16 withstood 8.7 MPa tensile stress, maintained a storage modulus of 5.52 MPa at 160°C, generated a blocking stress of 2.21 MPa, and achieved 31.24% actuation strain, 631 kJ m^{- 3} volumetric work capacity, and 728 J kg^-1 gravimetric work density under a 175 g load. Residual photoreactivity further enabled adhesive-free welding, electrothermal lifting of a 1 kg load, gripping, and repair. This work establishes anisotropic crosslinker design as a molecular strategy for load-bearing LCE artificial muscles.