Electromagnetic interference shielding study in microwave and NIR regions by highly efficient Ag/ZnS and polyaniline-Ag/ZnS particles

The chemical oxidative polymerization and co-precipitation methods were employed for the preparations of polyaniline (PANI) and silver-doped zinc sulfide (ZnS) nanoparticles to be used for electromagnetic interference (EMI) shielding. PVC-based composite films were fabricated by the incorporation of Ag/ZnS and PANI-Ag/ZnS nanoparticles. These nanoparticles were first analyzed by X-ray diffraction and zetasizer for their crystal structure and particle size. Prepared nanocomposite films were then analyzed for various properties like electrical conductivity, transmission in the near-infrared region (700 nm to 2500 nm), and EMI shielding efficiency in the microwave region (0.1 GHz to 20 GHz). These parameters were characterized by DC Conductivity, NIR spectroscopy, and vector network analyzer. It was found that with the addition of the concentration of nanoparticles, both values of conductivity and shielding efficiency improved. The highest attenuation value in 0.1 to 20 GHz reached 52.5 dB in 0.1 to 20 GHz frequency for 20 wt% PANI-Ag/ZnS and < 0.5% transmission was evaluated in the NIR region.