Chemical functionalization of graphene oxide toward the tailoring of the interface in polymer composites

In this work, we demonstrated that the composites with strong interfacial interactions between graphene–matrix could achieve excellent mechanical properties even the dispersion of graphene is poor. In terms of the above reason, an epoxy resin was coupled onto graphene oxide (GO) sheets via the “grafting to” method. Since each epoxy chain bears two terminated epoxide groups, it is inevitable that one epoxy chain connects two GO sheets together, causing the crosslinking of GO layers via the epoxy chain. When blending these resultant GO (GO–epoxy) with polycarbonate (PC), the dispersion was less-than-ideal due to these crosslinking. However, the residue active sites in the grafted epoxy chains, such as the unreacted epoxide groups as well as hydroxyl groups, could further react with PC carbonate to form chemical bonds, leading to strong interfacial interactions between the matrix and GO sheets. Owing to these strong interfacial interactions, the enhancement of the mechanical properties of PC/GO–epoxy composites was significantly higher than that of PC/(GO/epoxy) samples, as well as those shown in other similar works on thermally reduced graphene oxide (TRG)/PC composites with better dispersion.