Scalable and eco-friendly production of flexible, hierarchical porous MXene/polyimide composites with superior electromagnetic interference shielding

Abstract

MXene-based composites are widely recognized for their exceptional electromagnetic interference (EMI) shielding capabilities. While incorporating porous structures can enhance shielding efficiency, achieving scalable and uniformly distributed porosity remains a significant challenge. Here, we report the fabrication of large-area, flexible, and porous MXene/polyimide (PI) composite films using a water-borne polyimide (W-PI) matrix and polycarboxylate ether (PCE)-functionalized Ti3C2Tx MXene. The comb-like structure of PCE ensures uniform MXene dispersion, while its branched functional groups promote the formation of macro pores during thermal imidization. As a result, the composites exhibit outstanding EMI shielding effectiveness, reaching 66.1 dB in the X-band and 85.0 dB in the Ka-band. The porous architecture, generated through PCE evaporation and MXene thermal expansion, enhances both reflection and absorption pathways, further improving shielding performance. Additionally, the films demonstrate high electrical conductivity, exceptional flexibility with bending radii below 2 mm, and remarkable durability, retaining over 95 % of their shielding efficiency after 1000 bending cycles. This eco-friendly, water-borne processing strategy, combined with scalable slot-die coating, highlights the immense potential of these composites for next-generation applications in 5G communications, wearable electronics, and flexible devices.