Graphene oxide based moisture-responsive biomimetic film actuators with nacre-like layered structures

Hygroresponsive biomimetic actuators that convert chemical potential energy contained within the humidity gradient into mechanical deformation are of particular significance for realizing a sustainable society. Here, we report the preparation of nanocomposite films containing chitosan (CS) and graphene oxide (GO) with nacre-like brick-and-mortar microstructures by combination of water evaporation induced self-assembly and subsequent physical crosslinking in alkaline solution. The resulting hybrid films exhibit strong mechanical properties in both hydrated and anhydrous states, and the changes in physical properties between the two states likely result in perpetual mechanical reconfiguration. What's more, these films are capable of autonomous and continuous locomotion due to water exchange with the environment. The film actuator can lift objects 50 times heavier and transport cargos 10 times heavier than itself. Furthermore, we have assembled a motor that can move forward in response to humidity gradients, which provides proof of the utilization of this hybrid material in bio-inspired applications.