Simultaneous Reduction and Surface Functionalization of Graphene Oxide by Chitosan and Their Synergistic Reinforcing Effects in PVA Films

Reduced graphene oxide (RGO) was functionalized by chitosan (CS), and then the CS-functionalized RGO was incorporated into poly(vinyl alcohol) (PVA) to obtain the PVA-based nanocomposite films by a solution casting method. The CS-functionalized RGO was characterized by TEM and FTIR, indicating that graphite oxide was reduced successfully by CS and CS-functionalized RGO dispersed well in the PVA solution due to the strong interfacial interaction. PVA/CS/RGO exhibited superior enhancements in tensile strength and glass transition temperature than PVA/CS and PVA/RGO, suggesting the synergistic reinforcing effect between CS and RGO. The significant reinforcement for PVA/CS/RGO nanocomposite is attributed to the strong hydrogen bonding among RGO, CS, and PVA molecules. Furthermore, the barrier effect of RGO and the synergism between CS and RGO effectively promote the formation of continuous and compact chars and protect the inner materials from burning out; as a result, the fire safety properties of the composites are significantly improved.