A Moisture-Driven Actuator Based on Polydopamine-Modified MXene/Bacterial Cellulose Nanofiber Composite Film

As a new 2D material, MXene (Ti3C2Tx) shows great potential as a smart multifunctional humidity-responsive actuator due to its high hydrophilicity and conductivity but suffers from ambient oxidation and mechanical brittleness. Inspired by the mussels, the authors overcome these weaknesses by designing and fabricating a nacre-like and lamellar-structured composite film that consists of polydopamine-modified MXene and bacterial cellulose nanofibers, which shows improved properties as a moisture-driven actuator. The actuator has high conductivity (2848 S cm(-1)), excellent tensile strength (406 MPa), and toughness (15.3 MJ m(-3)). Moreover, the actuator is highly sensitive to moisture with the advantages of fast response (1.6 s), large deformation (176 degrees), and high actuation force output (6.5 N m(-2)). It is additionally demonstrated that the actuator works as the electrical switch, robotic arm, and motor in a moisture-driven manner. Overall, it is believed that this work improves the drawbacks of current MXene-based actuators, laying the groundwork for their wider applications as moisture-driven devices.