Ageing of thermomechanical and elastocaloric response of liquid crystalline elastomers

Main-chain liquid-crystalline elastomers were examined to assess their long-term thermomechanical stability and elastocaloric performance under repeated uniaxial actuation. The monodomain samples, prepared with tunable crosslink densities and well – defined nematic – isotropic (N–I) transitions, were subjected to up to 1,000,000 stretch – retract cycles using a custom extensometer capable of simultaneous strain, stress, and temperature measurements. Relatively small mechanical fatigue and absence of cracking and delamination were observed throughout the test duration, demonstrating excellent mechanical resilience. Repeated cycling produced a gradual enhancement of the elastocaloric temperature change, reaching a steady-state increase after several thousand cycles, consistent with stress-induced stabilisation of mesogenic alignment. Concurrently, the N-I transition temperature decreased by approximately 13 K, indicating partial network relaxation and reorganisation under prolonged loading. These results show that cyclic actuation can improve elastocaloric responsiveness while preserving structural integrity, highlighting MC-LCEs as robust and sustainable candidates for next-generation solid-state heat-management technologies.