Enhancing interface performance: Designing a novel energy‐absorbing coating for carbon fiber composites with brittle shells and flexible spherical cores

Abstract Surface modification of carbon fiber (CF) is one of the significant technical challenges for improving the interfacial properties of carbon fiber/polymer composites and thereby enhancing their mechanical properties. In light of the design principle of the core‐shell structure characterized by external rigidity and internal flexibility, this study probed into the potential interfacial mechanisms within carbon fiber composites, aiming to enhance their mechanical integration and overall performance. Through simple steps, polyurethane nanospheres were coated in silica and successfully deposited on the surface of carbon fibers, which maximizes the mechanical properties of carbon fiber composites without compromising their original strength. The results showed that compared with the composite material prepared from desized CF, the tensile strength of carbon fiber monofilament with successfully deposited PU‐SiO 2 nanospheres on the surface was successfully maintained. This method resulted in a maximum increase of 40.45% in interlayer shear strength of the composite. The fracture mechanism of the composite under stress was elucidated through analyses of transverse and longitudinal fracture morphology, further advancing the interface theory of carbon fiber reinforced polymer (CFRP). This provides innovation for the design and development of non‐destructive carbon fiber surface modification technology. Highlights Novel energy‐absorbing coating for carbon fiber composites. Brittle shells with flexible spherical cores enhance interface performance. Coating design improves the mechanical properties of composites. Study demonstrates a significant impact on material durability. Potential applications in the aerospace and automotive industries.