Light‐Responsive 4D Printing of Carbon Nanotube‐Liquid Crystal Elastomers for Directional Actuated Bending and Biomimetic Robotics

The alignment of liquid crystal mesogens greatly influences the behavior of liquid crystal elastomers (LCEs). Light irradiation generates temperature gradients, prompting photothermal-responsive LCE actuators to deform in response to the illumination direction. This study introduces a novel 4D printing method using LCE-carbon nanotube (CNT) composites to enhance the photoresponse efficiency of printed LCEs. Unlike previously reported mechanisms, our printed actuators achieve consistent directional actuation irrespective of light direction through precise control over liquid crystal mesogen alignment. We systematically assess the performance of single LCE-CNT fibers, examining light intensity dependence, actuation strain, temperature distribution, and cyclic loading capacity. The printed single-layer LCE films demonstrate approximately 50% reversible actuation strain and can lift objects exceeding 250 times their weight. Moreover, the printed laminated LCE structures exhibit directional bending deformation independent of illumination direction. Leveraging these advancements, we develop printed LCE-based biomimetic robots capable of diverse functions, including grasping, crawling, and swimming. The proposed 4D printing method and results offer new insights into the fabrication of soft materials and provide valuable references for the design and application of LCE-based photoresponsive soft machines.