Sizing agent induces the oriented attachment of 2D nanosheets for preparing high-performance carbon fiber composites

Inducing highly oriented 2D nanosheets to create a mussel-inspired interface phase on the carbon fiber (CF) surface to enhance its composites' strength and toughness has become a great challenge. In this study, a novel coating was synthesized to induce the graphene oxide (GO) oriented distributed on the CF surface while constructing a biomimetic "Brick-and-Mortar" structural interface phase, which simultaneously promoted the strength and toughness of CF composites. Acting as a sizing agent, di-pyrene terminated PEG (py-PEG-py) facilitates abundant pi-pi* stacking interactions, and enables flexible chain segment motion during interface fracture of composites, as well as effectively improving the toughness of composites. Eventually, the formation of a superior mechanism on the CF surface results in remarkable properties for composites, including an interfacial shear strength (IFSS) of 99.3 MPa, interlaminar shear strength of 93.2 MPa, and flexural strength of 1430 MPa. The tensile strength and toughness increased to 1777 MPa and 45.0 MJm(-3), respectively. Simultaneously, the continuous thermal conduction pathway produced by the oriented attachment of GO on the CF surface increased in-plane thermal conductivity. The reinforcing mechanisms of the unique mussel-inspired coating were systematically investigated. This work opens up an effective and scalability avenue for obtaining high-performance CF composites.