Interplay of optical, thermal, and electromagnetic properties in a silver-coated polypyrrole/carbon black composite for C- and X-band shielding

The escalating challenge of electromagnetic pollution drives the need for high-performance shielding materials. This study develops a lightweight, multifunctional composite by synthesizing a polypyrrole/carbon black (PPy/CB) matrix via in situ chemical oxidative polymerization and enhancing it with a nanostructured silver coating applied by chemical spray pyrolysis. A comprehensive characterization protocol, including FE-SEM, XRD, FT-IR, TGA, DSC, and UV-Vis spectroscopy, confirmed successful composite formation and revealed tailored material properties. The optimal composite (5 wt% CB with Ag coating) demonstrated a high electrical conductivity of 2.24×10⁻ ⁴ S/cm and exceptional EMI shielding effectiveness, reaching − 45 dB in the X-band (8.2–12.4 GHz) and − 30 dB in the C-band (4–8 GHz), governed by a low skin depth that decreased with frequency. The material also exhibited a tunable optical band gap, reduced from 5.88 eV to 5.79 eV, and enhanced thermal stability, with a decomposition temperature increased to 717°C. With a uniform silver coating thickness of ~ 246.3 nm, this composite integrates electrical, optical, and thermal functionalities, positioning it as a robust, multifunctional candidate for next-generation EMI shielding in advanced electronics and telecommunications.