Honeycomb Polyimide/ <scp>MXene</scp> Composite Aerogels With Excellent Electromagnetic Interference Shielding and Thermal Properties

ABSTRACT Lightweight and multifunctional electromagnetic interference (EMI) shielding materials are in urgent demand for advanced electronic devices used in harsh environments. In this work, honeycomb PIA‐Cu@MXene composite aerogels with excellent electromagnetic shielding and thermal properties were prepared through a synergistic strategy of cation–π interaction‐guided structural control, directional freeze‐drying, and repeated vacuum impregnation. Cu 2+ ‐mediated cation–π interactions contributed to a uniform and highly oriented honeycomb structure, which improved the mechanical robustness of the material. Meanwhile, uniformly dispersed Ti 3 C 2 T x MXene nanosheets constructed a continuous three‐dimensional conductive network. The aerogels exhibited outstanding absorption‐dominated EMI shielding performance in the X‐band. At 3 mm, the total shielding effectiveness (SE T ) of the optimized composite (PIC 0.2 M 6 with 20 mol% Cu 2+ and 6 mg mL −1 MXene suspension) was 22% higher than that of the copper‐free counterpart (PIC 0 M 6 ). The SE T reached 53.2 dB (specific shielding effectiveness SSE/ t ≈1642 dB cm 2 g −1 ) at 5 mm and 86.1 dB at 7 mm. The composite also possessed low thermal conductivity (~0.0511 W m −1 K −1 ) and good thermal stability, while maintaining stable shielding performance (SE T &gt; 20 dB) under liquid‐nitrogen freezing, high temperature, and ultrasonic treatment. This study provides an effective structural and interfacial design for developing lightweight, mechanically stable polymer/MXene‐based EMI shielding materials with enhanced thermal management.