Bioinspired thermal/light-tunable actuators based on predesigned tilted liquid crystal actuators

Smart material-based actuators have attracted much interest because of their envisioned applications in the fields of soft robotics, sensors, and artificial muscles. In this study, we fabricated liquid crystal (LC) actuators via polydopamine (PDA) assistance based on controlling the order parameters. The irregular aggregation of PDA particles coated on the LC film surface was evaluated. To synthesize LC actuators, a predesigned glass sample cell filled with tilt-arranged LCs was fabricated. The LC mixtures were polymerized by 254 nm UV irradiation in glass sample cells. The polymerized LC films showed reversible bending and helical motions depending on predesigned molecular arrangement of the films. This phenomenon was attributed to the phase transition from monodomain to isotropic LC films triggered by temperature and near-infrared light exposure. Adding of chiral dopant shows much higher curling efficiency on thermal stimulation. A hand-shaped actuator with gripping ability was prepared from the synthesized LC networks. The near-infrared light sensitivity of the LC networks was further enhanced using PDA coated on the surface. The observed results suggested that the synthesized LC actuators effectively converted thermal energy and photo-energy to mechanical power. These predesigned LC actuators hold potential for applications as artificial muscles and in micro robotics. Graphical abstract A series of thermally tunable liquid crystal elastomeric films was synthesized. Reversible shape variation controlled by temperature or light was achieved based on the order parameter control via the assistance of polydopamine.