Hierarchically porous polyimide foam sheets with outstanding electromagnetic interference shielding and microwave absorption characteristics

With the increasing severity of electromagnetic (EM) pollution, conductive porous materials have been widely used as effective electromagnetic interference (EMI) shielding materials to protect electronic equipment and human health. Although conventional conductive porous materials exhibit better impedance matching and lower EM wave reflection than metal-plate-based shielding materials. It remains challenging to overcome their poor mechanical strength and large thickness. In this study, we fabricated hot-pressed hierarchically porous polyimide foam (PF)/carbon black (CB)/Ni–P and PF/CB/Fe 3 O 4 –P composites with continuous conductive pathways using a chemical foaming and hot-pressing strategy. Benefiting from the continuous conductive pathways and hierarchically porous architecture, PF/CB/Ni–P containing 80 wt% Ni nanoparticles achieved a maximum EMI shielding effectiveness (EMI SE) of 60.7 dB in the X-band at a thickness of 5 mm. Meanwhile, the thicknesses of PF/CB/Fe 3 O 4 –P and PF/CB/Ni–P were further reduced by the hot-pressing strategy, exhibiting optimal absorption coefficients (A) of 0.51 and 0.68, respectively. The results demonstrate that this preparation method achieves excellent comprehensive performance, including enhanced mechanical strength and absorption-dominated EMI shielding, providing a promising approach for designing adaptive EMI shielding systems for aerospace and electronic applications. Download: Download high-res image (349KB) Download: Download full-size image