Interfacial reinforcement of composites by the electrostatic self-assembly of graphene oxide and NH3 plasma-treated carbon fiber

The introduction of graphene oxide (GO) on the surface of carbon fiber (CF) is considered an effective strategy to modulate the structure and properties of the fiber/matrix interface in CF reinforced polymer composites. However, the tensile strength of fibers often decreases due to the etching effect during treatment. In this study, a new method was proposed to graft GO onto fiber surfaces by electrostatic self-assembly. The results showed that -NH2 grafted onto CF through NH3 plasma treatment caused CF and GO to have opposite charges in deionized water; subsequently, they self-assembled to form CF@GO due to the electrostatic force. The tensile strength of CF@GO was 31.23% greater than that of pristine CF, which may be because the different sizes of GO repaired the surface defects on the CF with its multilayer restoration structure. The CF showed a noticeable improvement in surface wettability due to the GO coating. Moreover, the interfacial properties were significantly improved, with the interfacial shear strength (IFSS) of CF@GO increasing to 81.31 MPa, which was about twice that of unmodified CF. This work provides a promising strategy for nondestructive grafting nanoparticles on CF to build a strong interface in CF composites.