Composition-Dependent Structural, Optical, Dielectric, and Charge-Transport Properties of PVA/PANI–Graphene–Cobalt Nanocomposites

Abstract

The development of multifunctional polymer nanocomposites with tailored dielectric and charge-transport characteristics is vital for advancing next-generation energy storage technologies. In this work, poly(vinyl alcohol)/polyaniline/graphene–cobalt (PVA/PANI/Gr–Co) nanocomposites with different Gr–Co contents were prepared by the casting method. The structural, optical, dielectric, and electrical properties were systematically investigated. X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy confirmed the successful incorporation of graphene and cobalt into the PVA/PANI matrix. The observed changes were associated with enhanced interfacial interactions between PANI chains and graphene sheets. UV–Vis spectroscopy showed increased absorbance, and extinction coefficient after Gr–Co incorporation. The optical bandgap (Eg) also decreased, indicating enhanced electronic interactions within the nanocomposites. Dielectric measurements revealed a significant increase in the real part of the permittivity (ε′), particularly at low frequencies. This behavior was attributed to Maxwell–Wagner–Sillars (MWS) interfacial polarization at the polymer–filler interfaces. AC conductivity ( $${\sigma}_{ac}$$ ) also increased with Gr–Co incorporation. At 200 Hz, $${\sigma}_{ac}$$ increased from 1.42 × 10⁻ 4 S cm⁻ 1 for the pristine PVA/PANI blend (PP) to 9.92 × 10⁻ 3 S cm⁻ 1 for the PPGC3 nanocomposite. Electric modulus (M*) and impedance (Z*) analyses indicated non-Debye relaxation and a reduction in the bulk resistive contribution. These results demonstrate the potential of PVA/PANI/Gr–Co nanocomposites for flexible electronics, dielectric capacitors, and advanced energy-storage devices.