Synergistic enhancement of interfacial adhesion for CF / PEEK composites through carbene chemistry and water‐based self‐catalyzed cross‐linkable PENK‐NH 2 sizing agent

Abstract To address the issue of inadequate interfacial adhesion in carbon fiber/poly ether ether ketone (CF/PEEK) composites, an innovative approach that combines carbene chemistry and sizing treatment was meticulously designed to achieve remarkable synergistic enhancement. Specifically, cyano groups were chemical‐grafted on CF surface via carbene reaction. Meanwhile, a water‐based self‐catalyzed cross‐linkable PENK‐NH 2 sizing agent with good storage stability was prepared. Noteworthy, the presence of amino groups as blocking agents of sizing agent significantly accelerated the rate of cyano‐crosslinking, thus effectively avoiding the adverse effects of excessively prolonged cross‐linking period during composites preparation. As a result, robust interaction between cyano‐modified CF and PEEK was established by cross‐linking reaction, along with chemical bonds generated between amino groups of sizing agent and ketone groups in PEEK. The maximum interlaminar shear strength (ILSS) of CF‐CN‐1.5/PEEK composites was 22.0% and 57.0% higher than CF‐1.5/PEEK and CF/PEEK composites. Furthermore, the presence of cyano‐cross‐linked structure endowed interphase with outstanding solvent‐resistance, the mechanical properties of CF composites after solvent treatment were well‐preserved. The strong synergistic interfacial interactions facilitated by chemical bonds in different components provide an effective and fascinating methodology for producing high‐performance CF/composites. Highlights Water‐based self‐catalyzed cross‐linkable PENK‐NH 2 sizing agents for CF/PEEK were prepared. NH 2 was introduced to avoid the adverse effects of prolonged cyano‐crosslinking. Designed carbenoid motif with cyano group was grafted on CF via carbene chemistry. The interaction between sizing agent and CF was boosted by the cyano‐crosslinking. Mechanical properties of sized composites corroded by solvent were well‐preserved.