Designing structural-multifunctional CF/PEEK composites: achieving high performance, electromagnetic shielding, electrothermal deicing, and in-situ rapid repair through synergistic interfacial bridging and matrix engineering

The development of high-end equipment towards lightweight, intelligent designs places stringent demands on multifunctional integration in structural materials. Although thermoplastic carbon fibre-reinforced polyetheretherketone (CF/PEEK) composites offer advantages such as rapid processing and recyclability, their weak interfacial properties and limited functionality severely limit their potential for advanced applications, such as electromagnetic shielding and intelligent de-icing. This study, therefore, proposes an innovative, multi-scale, synergistic modification strategy that combines electrophoretic deposition interface engineering and matrix modification to manufacture CF/PEEK composites with enhanced mechanical properties and multifunctional integration. A three-dimensional carbon nanotube reinforcement layer was formed on the surface of the carbon fibre via electrophoretic deposition (EPD). Concurrently, the incorporation of graphene nanoplates (GNPs) and carbon nanotubes (CNTs) into the PEEK matrix via blending formed an interfacial bridging-matrix co-permeation three-dimensional structure. Experiments were conducted on the mechanical properties, electrical heating performance, electromagnetic shielding capabilities, and in-situ rapid repair capacity of synergistically reinforced CF/PEEK composites. The results indicate that the interlaminar shear strength (ILSS) and flexural strength of the synergistically reinforced composites increased by 113.1% and 121.6%, respectively, compared to the original composite. Electromagnetic shielding performance improved by 92.5% (65.06 dB), and the composites exhibited excellent electrical heating performance, reaching 113.9°C at 3 V/300 s, with stability maintained after 10 cycles. The mechanical properties recovered to 77.8% of the original composite after in-situ rapid repair, and the shielding effectiveness was restored to 96.4%. This work provides new insights and broader application prospects for designing next-generation structural-functional integrated thermoplastic composites for high-end equipment applications.