Reinforcing the physical properties of PVA/PVP with ferrous chloride for optoelectronic and antibacterial applications

Abstract

Abstract The present study investigated the composition, physical characteristics, and antibacterial efficacy of Polyvinyl alcohol/Polyvinylpyrrolidone (PVA/PVP) composite films containing different percentages (0–12%) of ferrous chloride (FeCl₂) by the solution casting method. XRD and FT-IR measurements indicate a significant increase in amorphous and substantial interactions between the polymer and filler with the addition of FeCl 2 . The composites exhibited enhanced thermal stability as evidenced by TGA, with the residual weight at 800 °C increasing from 0.21% for the pure sample to 6.28% for the sample containing 12 wt% FeCl 2 . The optical analysis reveals a significant decrease in the direct band gap, diminishing from 5.09 eV for the pure sample to 2.76 eV at 12% FeCl 2 , hence improving its applicability in optoelectronic applications. The films exhibit paramagnetic characteristics, with a saturation magnetization (Ms) of 0.055 emu/g at a 12 wt% FeCl 2 concentration. Hopping conduction and dielectric analyses reveal a marked improvement in both the dielectric constant and AC conductivity, attaining their highest values at a FeCl₂ concentration of 10 wt%. The barrier height decreases as the temperature and FeCl₂ content increase. Impedance spectroscopy exhibited an angled spike at low frequencies and a semicircular arc at high frequencies, indicating non-Debye relaxation behavior consistent with equivalent circuit models. Furthermore, the composites showed potent antimicrobial efficacy against both Gram-negative bacteria (Klebsiella pneumoniae and Escherichia coli) and Gram-positive strains (Staphylococcus aureus and Bacillus subtilis), suggesting their potential for multifunctional optoelectronic and antimicrobial applications.