Carbon Fiber Reinforced Polymer Composites Using Nanoscale MXene-CNT Interfacial Engineering for Mechanical and Electromagnetic Shielding

Surface modification of carbon fibers (CFs) is critical for achieving high-performance and multifunctional CF-reinforced composites. In this work, a synergistic interfacial engineering strategy was developed by co-grafting aminated MXenes and carbon nanotubes (CNTs) onto CF surfaces after nitric acid oxidation. The successful co-grafting of nanomaterials with different dimensionalities constructed a robust and multifunctional interfacial layer, whose effects on wettability, tensile strength, electrical conductivity, Interlaminar shear strength (ILSS), mechanical properties, and electromagnetic interference (EMI) shielding performance of composites were systematically investigated. FTIR and XPS confirmed the introduction of abundant polar functional groups and a roughened surface morphology, resulting in improved interfacial wettability and adhesion with the epoxy matrix. Benefiting from the synergistic interfacial modification, the CF-MXenes/CNTs@epoxy composites exhibited increases in mechanical performance, with ILSS and flexural strength increasing by 32.57% and 125.5%, respectively, compared with unmodified CF composites. Meanwhile, the interconnected conductive network formed at the modified fiber−matrix interface endowed the composites with excellent EMI shielding capability, achieving a total shielding effectiveness of 38.21 dB in the X-band, dominated by absorption. The simultaneous improvement in mechanical properties and EMI shielding performance originates from the synergistic effects of chemical bonding, mechanical interlocking, conductive network construction, and interfacial polarization.