Hygro-Dynamic and Conductive Actuator That Restructures and Heals by Water

The prospects of endowing stimuli-responsive materials with various life-like behaviors are promoting the development of intelligent robotic and electronic devices. However, it is challenging to incorporate stimuli-responsive actuating and healing capabilities into one single material system. Herein, the design and assembly of humidity-responsive thin films composed of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and sodium carboxymethyl cellulose (NaCMC) forming a conducting polymer composite through a physically cross-linked and hydrogen-bonded supramolecular network are described. Owing to its enhanced dynamics of hydrogen bonding at an elevated humidity, the PEDOT:PSS/NaCMC thin film exhibits a rapid humidity-responsive actuating performance in an environment with humidity gradient, as well as a repairing function of the structural, mechanical, electrical, and actuating properties after being damaged through a humidifying-drying cycle. Based on a combined analytical approach, a structural model is proposed for the rearrangement of the thin film when being exposed to stepwise humidity levels at multi-length scales. Due to the structural rearrangement powered by humidity variations, the film exhibits tunable actuating and healing performance, which makes it a promising candidate material for applications in intelligent soft robotics such as artificial muscles.