Enhancing the Interfacial Properties of Carbon Fiber/Epoxy Resin Composites by Constructing a Rigid–Flexible Structure of Carbon Nanotubes and Polyether Amine Onto Carbon Fibers

ABSTRACT To enhance the interfacial properties of carbon fiber reinforced polymer (CFRP) composites, a rigid–flexible interfacial structure was constructed by in situ growth of carbon nanotubes (CNTs) on the carbon fiber surface via chemical vapor deposition (CVD), followed by grafting polyether amines (PEA) with different molecular weights. The CNTs provided a rigid, high‐modulus structure enhancing mechanical interlocking and surface area, while PEA introduced a flexible, tough segment capable of forming chemical bonds with the epoxy matrix. The synergistic effect of the CNTs and PEA significantly improved interfacial adhesion and stress transfer efficiency. Interlaminar shear strength (ILSS) and interfacial shear strength (IFSS) of the composites were increased by 44.3% and 51.4%, respectively, compared with untreated CF composites. Furthermore, the optimal molecular weight of PEA was identified, balancing the rigid reinforcement and flexible energy dissipation. This work provides a promising strategy for tailoring interfacial architecture in CFRP composites and offers insights into the design of advanced structural materials with high strength and toughness.