writer：Jiang He, Peng Xiao, Jiawei Zhang, Zhenzhong Liu, Wenqin Wang, Liangti Qu, Yousi Chen*, Tao Chen
keywords：Graphene, Poly(dopamine), Composite thin film, actuator, Water gradients responsiveness
source：期刊
specific source：Adv. Mater. Interfaces, 2016, 3, 1600169-1600176
Issue time：2016年
Bilayer materials with different swelling behavior are usually used as actuator, yet still suffer from limitations such as poor interlayer adhesion during frequent bending, and the complex multistep fabrication process. Here, we present a new strategy that a structure of reduced graphene oxide/polydopamine (RGO-PDA) uniform composite thin film can serve as highly efficient actuator driven by moisture gradients. During the trigger by moisture from one side of the film, hydrophilic PDA can absorb water on the surface layers of RGO-PDA film to activate the swelling behavior, while the relatively hydrophobic RGO with ordered two dimensional lamellar structure hinders the diffusion of water molecules across the composite film. A unique bilayer structure in swelling difference along the lateral uniform composite thin film has thus been successfully in situ prepared upon the exposure to moisture gradient. This highly sensitive actuator has a very fast moisture gradient responsiveness with bending speed about 1000°/s and can serve as a "loader machine" with the ability to transport cargo 42 times heavier than itself.