Ag-polyaniline/α-Al₂O₃ ternary nanocomposites for enhanced electrical conductivity and EMI shielding performance

A ternary hybrid composite of silver-polyaniline/α-alumina (Ag-PANI/α-Al₂O₃) was successfully synthesized using a straightforward in situ polymerization method in an HCl solution. The composite's structural, morphological, and electrical properties were systematically analyzed to assess its potential for electrical conductivity and electromagnetic interference (EMI) shielding applications. X-ray diffraction (XRD) confirmed the formation of Ag-PANI and the incorporation of α-Al₂O₃ nanoparticles (NPs), with a noticeable reduction in crystallinity upon α-Al₂O₃ additions. Fourier-transform infrared (FTIR) spectroscopy validated PANI polymerization and its interaction with α-Al₂O₃. Field emission scanning electron microscopy (FE-SEM) revealed a uniform dispersion of α-Al₂O₃ within the Ag-PANI matrix, facilitating the development of a compact structure. Electrical conductivity analysis demonstrated that the AC conductivity (σac) exhibited a frequency-dependent trend, reaching a peak value of 8.7 × 10⁻⁵ S/cm at 6 wt% α-Al₂O₃. Dielectric studies indicated a significant enhancement in the dielectric constant, attributed to interfacial polarization. EMI shielding analysis using a vector network analyzer (VNA) showed that the 6 wt% α-Al₂O₃ composite achieved optimal shielding (∼37.4 dB) in the S-band (8.2–12.4 GHz), effectively attenuating over 90 % of incident electromagnetic waves. The superior electrical and dielectric properties of the composite arise from the synergistic interaction between PANI, α-Al₂O₃, and AgNPs, making it a promising candidate for advanced EMI shielding applications.