Structural and optical properties of polyvinyl alcohol/copper oxide (PVA/CuO) nanocomposites

Abstract

In the present investigation, pristine polyvinyl alcohol (PVA) and copper oxide (CuO) incorporated nanocomposite films have been fabricated via simple solution cast technique. The structural and optical properties of the prepared films were studied in detail. Various concentrations of CuO NPs (0.1–0.4 wt %) incorporated in the PVA film were prepared. The X-ray diffraction (XRD) profiles indicate the presence of CuO nanoparticles (NPs) in PVA film. XRD results indicate that, the CuO NPs were successfully incorporated into the PVA host matrix with no additional impurity peaks. The obtained CuO NPs belong to the monoclinic phase as confirmed by the XRD results. The peak observed at 2θ = 19.4° evident for the formation of semi crystalline PVA polymer. The average crystallite size of the prepared NPs was observed to be ∼0.52 nm. The vibrational bands present in the prepared films were confirmed by the Fourier transform infra-red spectroscopy (FTIR) plots. The presence of the NPs in the films was further investigated with the help of Raman spectra. UV–visible optical absorption spectra was recorded to evaluate the band gap values of the prepared films. The band gap value for pristine PVA was found to be 5.35 eV and it decreases with increase of CuO NPs concnetration owing to the change in the electronic structure of the pure PVA. The dielectric properties were also evaluated and it was found that, with increase in the CuO NPs concentration the dielectric constant also increases owing to the increase in density of states leading to the formation of polarization. The optical conductivity of the prepared nanocomposites increases with increase in the NPs concentration due to the formation of the charge transfer complex. The obtained results reveal that, the addition of CuO NPs reduces the optical band gap of the PVA polymer films.