Bioinspired superhydrophobic light-driven actuators via in situ growth of copper sulfide nanoparticle on cellulose nanofiber

Abstract

Among stimuli-responsive actuators, light-driven hydroplaning actuators have attracted significant attention because of their controllable and contactless nature. However, manufacturing actuators with rapid dynamic responses to a single stimulus remains challenging. Herein, inspired by rove beetles and water striders, we developed superhydrophobic light-driven actuators based on the in situ growth of copper sulfide on cellulose nanofiber and subsequent modification with octadecyltrimethoxysilane. The actuators exhibited excellent superhydrophobicity (water contact angle of 160.6°) and the water contact angle was maintained above 150° under various harsh conditions (acid/base immersion, ultraviolet irradiation, heat treatment, and sandpaper abrasion). Under near-infrared (NIR) irradiation (808 nm, 1.4 W cm−2), excellent photothermal performance was achieved, with a photothermal-induced temperature change of 81.0 °C. Based on the mechanisms of superhydrophobicity, the Marangoni effect, and vapor jet flow, the light-driven actuators exhibited a rapid dynamic response (response time of 0.5 ± 0.2 s), ensuring fast linear motion (velocity of 8.7 ± 0.7 mm s−1) and flexible rotation (angular speed of 2.4 rad s−1) under NIR irradiation. Moreover, complex motions such as S-shaped, triangular, and circular motions were achieved by combining linear motion and rotation, which could facilitate obstacle avoidance, smart transportation, and contactless delivery.