Polyimide-based high-temperature-resistant films for electromagnetic-interference shielding

Heat-resistant electromagnetic-interference (EMI) shielding materials have received considerable attention for application in extreme environments. In this study, the surface of silicon carbide (SiC) particles were modified using a silane coupling agent. Polyaniline-coated SiC (mSiC@PANI) composites with core–shell structures were subsequently prepared through situ polymerization. Polyimide (PI), a special engineering plastic with excellent thermal stability, was synthesized by prepolymerization, and the resulting ternary PI/mSiC@PANI films exhibited high EMI shielding performance in the X and Ku bands. The EMI shielding efficiency of the composite films with a thickness of 2 mm reaches 35 dB owing to the high conductivity of PANI and interface effect between PANI and SiC, promoting the absorption and attenuation of EM waves. The introduction of high-temperature-resistant SiC filler significantly improves the high-temperature resistance of the PI-based composite films with the thermal decomposition temperature of 600°C, demonstrating their application at temperatures below 300°C for a long period and suitability for EMI shielding in complex environments.