Synergistic enhancement of interfacial adhesion for CF/PEEK composites through carbene chemistry and water-based self-catalyzed cross-linkable PENK-NH₂ sizing agent

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 waterbased self-catalyzed cross-linkable PENK-NH2 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 crosslinking 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 cyanocross-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.