Nanocellulose Incorporated\nLiquid Crystal Elastomers\nas Soft Actuators

Liquid crystal elastomers (LCEs) are potential soft actuators\nthat\nexhibit spontaneous reversible shape transformation with a substantial\ndimensional change. High strength, multiple controls over actuation,\nand faster response times are key parameters for the successful practical\napplication of LCEs. In this work, we explored the influence of cellulose\nnanocrystals (CNCs) as fillers in LCEs to improve their strength without\ncompromising the elasticity and liquid crystal properties. This study\ndemonstrated that incorporating a certain amount of CNCs into LCEs\ncan produce a soft actuator composite having high mechanical strength,\na multi stimuli response (thermal and light-induced thermal actuation),\nand the ability to lift heavy objects. Five different wt %’s\nof CNCs (0.01–0.05 wt %) having an aspect ratio of ∼3.6\nwere incorporated during the preparation of the elastomer to obtain\nthe composites. The impact of the CNCs on the mechanical, actuation,\nand weight-lifting properties of the composites was studied. All of\nthe composite films displayed LC properties and good thermal stability.\nDespite the presence of CNCs, all of the composite films showed good\nthermal actuation. Among the composite films, the LCE containing 0.02\nwt % displayed a maximum ultimate stress of 1.99 MPa and a total elongation\nof 62.9%. This film displayed a shrinkage of 23% during heating. By\nusing an incandescent bulb source for light-induced thermal actuation,\nthe film was able to lift 300 g of weight, which is 1288 times its\ninitial weight. We highlight that the LCE-CNCs composite film (0.02\nwt %) has excellent mechanical stability, shape memory properties,\nand weight-lifting capability that can be beneficial for artificial\nmuscles and soft robotics.