Frequency-stable green EMI shielding in polyaniline-ferrite nanocomposites via dielectric and magnetic tuning

The need for advanced electromagnetic interference (EMI) shielding materials with minimal secondary radiation has driven interest in absorption-dominated or green EMI shielding systems. This work explored the development of efficient and frequency-stabilized green EMI shielding material based on polyaniline (PANI) by in situ incorporation of cobalt nickel ferrite (CNF) nanoparticles into the polymer matrix. EMI shielding effectiveness (SE) was measured in the K-band (18-26.5 GHz), achieving a maximum value of 68.96 dB for PANI/CNF10. All composites investigated in this study surpassed the commercial SE threshold of 30 dB, with shielding primarily governed by absorption. Reduced skin depth and high green index (GI) approaching unity confirmed their efficient absorption behavior. Further, multi-scale attributes of the composites were correlated to each other as well as to their EMI shielding behavior. Complementary optical, structural, and morphological analyses confirmed successful CNF integration and interaction with the PANI matrix. Dielectric and magnetic studies revealed enhanced AC conductivity, non-Debye relaxation, and improved coercivity, attributed to the synergistic effect of CNF addition into the PANI matrix. These results position PANI/CNF composites as promising green EMI shielding materials for next-generation electronic applications.