Graphene Oxide-Modified MXenes with Ti–O–C Covalent Bonding for Carbon Fiber Composites with Enhanced Interfacial Properties and Toughness

Introducing two-dimensional (2D) nanoreinforced materials on the surface of carbon fibers (CFs) is a promising strategy for overcoming the chemical inertness of CFs. However, disordered alignment and uneven dispersion of 2D nanoreinforced materials on the CF surface are the most critical issues that must be addressed. Herein, MXene (M) was functionalized using graphene oxide (G) to produce intercalated 2D reinforcement materials, and robust Ti–O–C covalent bonds were introduced to ensure that M and G have strong binding forces. An interface layer with a more ordered and compact “brick-and-mortar” structure was developed on the CF surface to obtain CF composites with high strength and toughness. Owing to the structure superiority, robust Ti–O–C covalent bonding, and abundant π–π interactions, the optimal CF composites achieved high strength and toughness, with a tensile strength of 1587 MPa and a toughness of 45 MJ m–3. Meanwhile, the interlaminar shear and flexural strengths increased to 82 and 1178 MPa, respectively. The reinforcing mechanisms of the unique interface layer on CF composites were systematically investigated via data analysis and modeling. This study provides a constructive design inspiration for fabricating high-performance CF-reinforced polymer composites, considerably expanding their applications.