Integrated construction of hierarchically porous polyimide aerogels with hollow MXene microspheres for ultra-lightweight absorption-dominated electromagnetic interference shielding

Conductive polymer composites often exhibit high electromagnetic interference (EMI) shielding effectiveness (SE) but suffer from strong reflection, leading to secondary electromagnetic pollution. Developing lightweight, absorption-dominated EMI shielding materials is thus crucial. Herein, a novel integrated strategy is proposed for the fabrication of ultra-lightweight polyimide (PI) composite aerogels, characterized by hierarchically porous structures and hollow MXene microspheres. MXene-wrapped polystyrene (PS) microspheres are first assembled and incorporated into a poly(amic acid) salt (PAAs) solution. Subsequent directional freezing, freeze-drying, and a two-step thermal treatment (imidization at 300 °C followed by PS removal at 450 °C) yield PI aerogels embedded with uniformly distributed hollow MXene microspheres. This unique hierarchical structure creates abundant heterogeneous interfaces and multi-scale pores, facilitating internal scattering and dissipation of electromagnetic waves. The optimized composite aerogel (PHM580–10wt%) achieves an exceptional X‑band EMI SE of 52.3 dB at an ultralow density of 0.038 g cm⁻³ and a thickness of 3.0 mm with a high absorption coefficient (A) of 0.57, demonstrating an absorption-dominated EMI shielding mechanism and achieving a superior specific shielding effectiveness of 4637 dB·cm²·g⁻¹ . Moreover, the aerogel exhibits excellent compressive resilience and stable EMI shielding performance (96% EMI SE retention after 100 cycles of compression), alongside notable thermal insulation and flame retardant properties. This work provides an effective approach to designing high-performance, ultra-lightweight, and absorption-dominated EMI shielding materials for advanced electronics.