Functionalized carbon fibers with MXene via electrochemistry aryl diazonium salt reaction to improve the interfacial properties of carbon fiber/epoxy composites

In this study, a simple and rapid grafting method, without damage to carbon fiber (CF), is proposed to graft MXene nanosheets onto the surface of CF via covalent bonds through electrochemical aryldiazonium salt reaction and using p-phenylenediamine molecule as a bridge so as to enhance the interfacial properties of CF/epoxy (EP) composites. The surface morphology, chemical activity and wettability of the modified CF were characterized by scanning electron microscope, atomic force microscopy, X-ray photoelectron spectroscopy and dynamic contact angle test. The effect of such surface modification method on the mechanical properties was also evaluated. Compared with untreated CF, the interfacial shear strength of MXene functionalized CF reached 123.86 MPa, increasing by 33.5% while the tensile strength is not reduced. The interfacial enhancement mechanism might be the strong physical and chemical interactions between MXene and EP resin matrix produced by the rough structure and high surface activity of MXene. This work may provide a new idea with a facile and rapid approach to modify the surface of CF and improve the interfacial properties of composites without degrading the mechanical property of pristine CF.