Chemical bond‐regulated heterogeneous interface engineering strategy for simultaneous enhancement of mechanical and electromagnetic interference shielding performance in <scp>Carbon fiber‐reinforced thermoplastic</scp> composites

Abstract Carbon fiber‐reinforced polymer composites (CFRPs) that integrate structural and functional properties, such as excellent electromagnetic interference (EMI) shielding and mechanical strength, are crucial for advanced material applications. However, simultaneously achieving both high EMI shielding effectiveness (SE) and mechanical strength in CFRPs remains a significant challenge, primarily due to the low conductivity of resin matrices and complex interfacial interactions. In this study, we propose a chemical bond‐regulated heterogeneous interface engineering strategy to achieve concurrent improvements in EMI shielding and mechanical properties of CFRPs. The composites, simultaneously enhanced through a collaborative effect of the silane coupling agent 3‐aminopropyltriethoxysilane (KH550) and carbon nanotubes (CNTs), attained an EMI SE of 78.0 dB, which constitutes a 188.8% enhancement compared to the baseline carbon fiber‐reinforced polyamide 6 (CF/PA6) composite. Additionally, the interlaminar shear strength (ILSS) increased by 61.3%, representing one of the best results in the literature. Detailed investigations revealed that the formation of conductive networks and heterogeneous interfaces between CF and KH550 and CNT/PA6 with KH550, along with chemical bonding, significantly contribute to electromagnetic wave attenuation and mechanical reinforcement. This study presents a novel design approach for developing next‐generation high‐performance CFRPs with efficient EMI shielding and mechanical robustness. Highlights KH550 &amp; CNT create interfaces, boosting EMI shielding &amp; mechanical strength. Multiple heterogeneous interfaces improve the EMI shielding performance. Chemical bonds are key for mechanics boost. EMI shielding effectiveness increased to 78.0 dB (188.8% above baseline) Interlaminar shear strength improved by 61.3%, among the best reported.