Bio‐inspired metal ion coordination cross‐linking synergistic strategy to enhance the interfacial properties of carbon fiber composites

Abstract The application of carbon fiber (CF) in carbon fiber composites has faced limitations due to its surface chemical inertness. To overcome this challenge, this study draws inspiration from metal ion‐enhancing exquisite hierarchical and multiphase structures observed in biological materials. The research proposes a novel approach to enhance the interfacial bonding of CF/Epoxy (E‐51) composites by utilizing tannic acid (TA), carboxylated cellulose nanocrystals (CNCs), Fe 3+ ions, and polyvinyl alcohol (PVA). This approach aims to create hydrogen bonding and metal synergistic networks on the surface of CFs through metal ion (M n+ ) coordination cross‐linking synergistic (MCCS) interactions. Implementing MCCS strategy resulted in significant improvements in the mechanical properties of the hybrid reinforcements compared to untreated CF composites. The flexural strength, flexural modulus, interlaminar shear strength, and interfacial shear strength experienced respective increase of 50.9%, 72.8% 59.4%, and 61.9%. Moreover, the damping properties of the composites exhibited significant improvements. These positive outcomes can be attributed to the formation of chelation and dense hydrogen bonding networks between TA, Fe 3+ , CNC, and PVA. Furthermore, CNC and PVA formed cross‐linked nanolayers that effectively deflected cracks and facilitated high energy consumption at the interface. This proposed approach provides a sustainable, environmentally friendly, and efficient method for surface modification in the preparation of high‐performance fiber composites. Highlights Metal ion (M n+ ) coordination cross‐linking synergistic strategy is proposed. Tannins/Fe 3+ /CNCs/PVA form multiphase nanolayers. Metal ion coordination cross‐linking enhances delicate multiphase structures. The prepared carbon fiber composites exhibit excellent properties. The as‐prepared carbon fiber composite has promising applications.