Spectroscopic and Mueller matrix characterization of functionalized PVA/ZnO nanocomposite film

The ZnO-reinforced PVA nanocomposite films containing different concentrations (by wt%) of ZnO nanoparticles were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-visible spectroscopy, and Mueller matrix polarimetry (MMP). The X-ray diffraction results reveal that the crystallinity of PVA/ZnO nanocomposite film has improved by 1.6 times compared to pure PVA film due to the incorporation of ZnO nanofiller at 3 wt% concentration. Incorporation of ZnO nanofiller into the PVA matrix induced clear modifications in the optical response of the nanocomposite film. The nanocomposite film showed a gradual reduction in transmittance, accompanied by a significant increase in absorbance in the UV-Visible range with rising ZnO content. The direct band gap of the PVA film decreased from 5.5 eV to 4.25 eV at 3 wt% concentration of ZnO. Further polarization-based investigation has been done using the Mueller matrix polarimetry technique. MMP reveals the structural and morphological changes in PVA/ZnO nanocomposite film due to the incorporation of ZnO nanofiller through Mueller decomposed parameters, depolarization, diattenuation, and retardance. Retardance values have shown a significant change with the concentration of ZnO nanofiller in the nanocomposite films. There is a decrease in the retardance with increasing concentration of ZnO, confirming the reduction in the anisotropy of the samples.