Electromagnetic wave absorption polyimide fabric prepared by coating with core–shell NiFe2O4@PANI nanoparticles
The nickel ferrite@polyaniline/polyimide (NiFe2O4@PANI/PI) fabric was prepared by coating the PI fabric with core–shell NiFe2O4@PANI nanoparticles to obtain an excellent microwave absorption performance. Firstly, a microwave absorbing agent was fabricated by dispersing the pre-synthesized core–shell NiFe2O4@PANI nanoparticles into epoxy monomer, in which the covalent bonding between epoxy groups and amine groups from PANI made them uniformly disperse. Then the agent was coated on to the PI fabric to a thickness of 0.12 mm. The results of field effect-transmission electron microscopy and scanning electron microscopy demonstrated the core–shell structure of NiFe2O4@PANI and the composite structure of the NiFe2O4@PANI/PI fabric. The resultant fabric possessed a high microwave attenuation property with a minimum reflection loss value of −19.2 dB (>90% attenuation) at 16.1 GHz and the effective absorption bandwidth was 5.1 GHz. This high performance was attributed to the uniform dispersion of core–shell NiFe2O4@PANI nanoparticles, better impedance matching and intensive synergistic effect between dielectric loss caused by the PANI shell and magnetic loss from the NiFe2O4 core. The favorable flexibility, processability and high tensile properties gave the composite fabric a long service time under pressure or foldable conditions. Furthermore, this process was environmentally friendly as no organic solvent was used in the whole process and the NiFe2O4@PANI/PI fabric could potentially be applied in microwave absorbing fields.