This work researched the effects of graphene oxide (GO) content and asymmetric patterning on the humidity response performance of cellulose nanofibers (CNF)/GO films. Firstly, CNF/GO composite films with asymmetric structure and different GO contents were prepared by vacuum filtration and surface imprinting technique. Then, the effects of GO content on the surface structure, mechanical properties, transparency and humidity response of the CNF/GO films were studied. With the help of molecular dynamics simulation and finite element analysis, the mechanism of GO content and asymmetric patterning affecting the humidity response performance of the composite films was explained theoretically. Besides, the application of CNF/GO composite films in bionic blade, proximity sensor and moisture-driven electricity generator was studied. The results show that the addition of GO with abundant hydrophilic functional groups can promote the water molecules adsorption upon the composite films and improve the flexibility of the composite films. Asymmetric patterning which is similar to biological ion channel, can obviously improve the transmission rate of water molecules on the films and enhance the deformation degree of the composite films under the same stress. This work provides a novel idea for the CNF/GO intelligent materials design, and has great significance for the utilization of natural polymer materials.

cellulose nanofibers; graphene oxide; film; humidity sensing