Effect of Interlayer Interactions on the Dynamic Self-Stiffening Behaviors of Graphene Oxide-Based Films

The responsive behaviors of graphene oxide (GO)-based films under external straining make it possible to develop man-made adaptive materials. Some researches have suggested that GO nanosheet alignment plays important roles in dynamic stiffening behaviors; however, the effects of inter-sheet interactions have not been thoroughly investigated. In this study, the GO interlayer interactions are tuned by third components, including hydrophilic nanofumed silica (SiO2) nanoparticles, chemically modified SiO2 nanoparticles, and waterborne polyurethane particles, and their stiffening behaviors and structural changes during periodic external straining are systematically characterized. During external dynamic straining, the storage modules (E ') of GO-based composite films increases up to 55.5% after 12 h. It is observed that the interlayer adhesion is important for the self-stiffening behaviors of GO-based films. The interaction types, including reversible H-bonding and non-reversible chemical bonding, play different roles on the structural-responsive behaviors. During external dynamic straining, the interlayer contact between GO nanosheets is improved, and the higher interlayer adhesion leads to improved mechanical properties, instead of the improvement of GO sheet orientation. These findings are helpful to better understand the responsive behaviors of nanomaterials as well as to develop new types of man-made adaptive materials.