Tailoring Interlayer Architecture of PBONF/MXene for Enhanced Interlaminar Fracture Toughness and Electromagnetic Interference Shielding in Carbon Fiber‐Reinforced Polymer

Interleaving is a strategy to enhance the interlaminar fracture toughness of carbon fiber‐reinforced polymer (CFRP) laminates and impart multifunctionality. In this study, two types of interlayers composed of poly( p ‐phenylene‐2, 6‐benzobisoxazole) nanofibers (PBONF) and Ti 3 C 2 T x MXene nanosheets are introduced into CFRPs. The layered PBONF/MXene film and porous PBONF/MXene aerogel are prepared by vacuum‐assisted filtration and freeze‐drying, respectively. The influence of interlayer architecture on the interlaminar fracture toughness and electromagnetic interference (EMI) shielding effectiveness is investigated. Mode I (G Ic ) and Mode II (G IIc ) fracture toughness are evaluated using double cantilever beam and end‐notched flexure tests, respectively. Compared to the pristine laminate, both interlayers improved fracture toughness, with the aerogel showing prominent effects, achieving G Ic and G IIc improvements of 86.26% and 48.66%, respectively. Fractography revealed that the porous structure of aerogel hindered crack propagation by inducing complex crack paths and greater energy dissipation. Furthermore, the film‐interleaved laminate exhibited an optimal EMI shielding effectiveness of 37.95 dB, due to enhanced internal absorption from MXene. These findings indicate that tailoring interlayer architecture impacts the balance between interlaminar toughening and EMI shielding, offering design pathways for multifunctional composites.