Facile Synthesis of Polyindole/Ni1-xZnxFe2O4 (x=0, 0.5, 1) Nanocomposites and Their Enhanced Microwave Absorption and Shielding Properties

The present work reports the fabrication of polyindole (PIN)/Ni1-xZnxFe2O4 (x = 0, 0.5, 1) nanocomposites as efficient electromagnetic wave absorbers by a facile in situ emulsion polymerization method for the first time. The samples were characterized through Fourier transform infrared spectroscopy, UV-vis spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, high-resolution transmission electron microscopy, and vibrating sample magnetometry. The resulting polyindole/Ni1-xZnxFe2O4 ( x = 0, 0.5, 1) nanocomposites offer better synergism among the Ni1-xZnxFe2O4 nanoparticles and PIN matrix, which significantly improved impedance matching. The best impedance matching of Ni1-xZnxFe2O4/polyindole (x = 0, 0.5, 1) nanocomposites was sought out, and the minimum reflection loss of the composites can reach up to -33 dB. The magnetic behavior, complex permittivity, permeability, and microwave absorption properties of polyindole/Ni1-xZnxFe2O4 (x = 0, 0.5, 1) nanocomposites have also been studied. The microwave absorbing characteristics of these composites were investigated in the 8-12 GHz range (X band) and explained based on eddy current, natural and exchange resonance, and dielectric relaxation processes. These results provided a new idea to upgrade the performance of conventional microwave-absorbing materials based on polyindole in the future.