Uniform Contraction and High Force Output of Photoresponsive Shape-Memory Polymer Actuators with Large Thickness Based on Vertical Distribution of Rare Earth Oxides

Light induced soft actuators have broad application prospects where non-contact stimulation and remote control are required. However, such soft actuators cannot achieve uniform contraction easily due to the weak penetration of light. Here, with the aid of vertical distribution of Sm2O3, Yb2O3, and Nd2O3 as selectively photothermal fillers along film thickness, a near-infrared (NIR) light (1064, 980, and 808 nm) induced soft actuator based on shape-memory polymer composites, which has a large thickness up to 2 mm is reported. The results show that tri-layer films present uniform contraction and could lift a weight of 101.44 g by 8 mm under simultaneous irradiations of three NIR light beams. It is believed that the vertical distribution of selectively photothermal fillers provides a new strategy to create light induced soft actuators that can present uniform shape reconfiguration and high pulling force, further filling the gap between material concept and engineering applications.