The incorporation of polypyrrole (PPy) in CS/PVA composite films to enhance the structural, optical, and the electrical conductivity

Abstract

Using the solution casting method, a blend of polyvinyl alcohol/chitosan (PVA/Cs) blend was prepared with different amounts of polypyrrole (PPy) to enhance the structural and electrical conductivity of the films. The miscibility and interaction between PVA/Cs were confirmed by FT-IR measurements by shifting and disappearing some bands suggesting that the PVA functional group interacted with every other functional group on the Cs side chain. For PVA/Cs/PPy, some band intensities varied, indicating the interaction between PPy and PVA/Cs. XRD showed that the addition of PPy to the blend leads to a noticeable decrease in the intensity of the diffraction peak at 2θ = 20.0° confirming the interactions have occurred between the PVA/Cs mixture and PPy. The UV–visible spectra indicate that increasing the amounts of PPy leads to a dramatic decrease in the energy band gap and an increase in the Urbach energy due to the creation of new energy levels that emerged between conduction and valance bands. After PPy was introduced, the polaron and bipolaron transition peaks at 416, 465, and 560 nm become apparent in the PL spectrum. The dielectric and the electrical properties were reported. The values of ε′ and ε′′ were stronger at low frequencies confirming the possibilities of interface polarization processes. The tan δ behavior diagrams have exhibited one peak trend in all samples shift toward higher frequencies as the temperature and PPy rise. The presence of the peaks was explained based on the electrical conductivity mechanism and dielectric behavior. The Cole–Cole plot displays a half one semicircle shape that explains the absence of contact effects. This semicircle expands as both temperature and PPy increase.