Construction of a Bioinspired CAT/TEPA–ZnO Mortise‐and‐Tenon Interface for Synergistically Enhancing the Interfacial Properties of Carbon Fiber Composites

Carbon fiber‐reinforced (CF) polymer composites often suffer from poor interfacial performance resulting from the smooth and nonpolar surface of CF, which results in weak interfacial adhesion with polymer matrices and consequently limits their practical applications. To address this issue, a bioinspired interfacial modification strategy based on a catechol (CAT)/tetraethylenepentamine (TEPA) coating and the in situ formation of ZnO nanostructures was developed. Specifically, an active CAT/TEPA layer was first constructed on the CF surface through the cross‐linking reaction between catechol and TEPA, which subsequently provided an effective framework for situ growth of ZnO nanosheets. The integration of ZnO nanosheets onto the CAT/TEPA‐functionalized carbon fiber surface created a cooperative interfacial reinforcement mechanism, in which chemical interactions and mechanical interlocking jointly contributed to interface strengthening, analogous to a bioinspired mortise‐and‐tenon configuration. As a result, the modified CF/EP composites exhibited increases of 45.4%, 65.0%, and 109.5% in bending strength, interlaminar shear strength, and interfacial shear strength in that order, compared with the untreated counterparts. The developed surface modification approach offers the advantages of operational simplicity, environmental compatibility, and economic feasibility, thereby presenting an effective strategy for the development and manufacture of high‐performance carbon fiber‐reinforced composites.