Electrostatic assembly induced cross-dimensional nano-interface design for enhanced mechanical and electromagnetic interference shielding properties of CF/PEEK composites

The weak interfacial bonding between carbon fiber (CF) and polyetheretherketone (PEEK) has constrained the mechanical performance and multifunctional potential of the CF reinforced PEEK composites. To overcome this challenge, an environmentally sustainable surface modification strategy for CF was developed, leveraging the synergy of cross-dimensional nanomaterials. Unlike conventional approaches where conductive carbon black (CB) is dispersed in resin matrices, this work pioneers the use of surface-charge-modified CB for direct fiber interfacial enhancement. Using the electrostatic self-assembly method, two-dimensional negatively charged MXene nanosheets and zero-dimensional positively charged conductive CB particles were precisely anchored onto the CF surface through electrostatic interactions. The innovative synergy of the cross-dimensional dual nanomaterials simultaneously enhanced the mechanical and electromagnetic shielding properties of the CF/PEEK composites. Compared with the unmodified CF/PEEK composite, the maximum improvements in flexural strength, flexural modulus, and interlaminar shear strength (ILSS) of the composite after modification were 73.4 %, 47.72 %, and 60.27 %, respectively. This is achieved through the synergistic effects of mechanical interlocking, electrostatic interactions, van der Waals forces, along with hydrogen bonds. Meanwhile, the optimal electromagnetic shielding performance of the modified composite reached 31.04 dB at the X-band, representing an increase of 33.56 %, which can mainly be ascribed to the uniform distribution of nanomaterials that enhance the conduction loss and multiple reflections. This scalable and eco-friendly pathway holds considerable application potential for constructing integrated structural-functional CF/PEEK composites.