Honeycomb-like Polyimide/Fe₃O₄@PPy foam for electromagnetic wave shielding with excellent absorption characteristics

Electromagnetic interference (EMI) shielding materials with low reflection and excellent microwave absorption characteristics are highly desirable for high-speed electronics devices to attenuate radiated emissions. Herein, we developed a highly absorption dominated composite EMI shielding foams with “honeycomb” structure through chemical foaming and subsequent in situ vapor deposition of polypyrrole (PPy) within polyimide (PI) foams. After the deposition of PPy, the obtained porous PI foams exhibit electrical conductivity of 2.7 × 10³ S/m. In addition, the composite foams demonstrate the highest absorption coefficient of 0.8 and EMI shielding efficiency of 41.1 dB with a thickness of 8 mm. Moreover, the optimal reflection loss (RL) of the composite PI/Fe₃O₄-20@PPy foam (PF/Fe₃O₄-20@PPy) reach up to −31 dB at 6.0 mm and ≤ −10 dB in the whole X band with a thickness of ≥4 mm. Moreover, the 3D porous structure of PI foam and favorable electrical conductivity of in-situ formed PPy film can contribute to the high sensing performance of PI@PPy foam (PF@PPy). This study provides a novel strategy for the development of lightweight, EMI shielding and microwave absorption materials for advanced applications in flexible anti-radiation and stealth devices.