Gamma rays induced modifications in the structural, optical and photoemission properties of PVA/TiO2 nanocomposite films

In the present study, nanocomposite films made of TiO2 (0.01 wt%) nanoparticles (NPs) embedded in polyvinyl alcohol (PVA) polymers were prepared via the solution casting technique. The PVA/TiO2 nanocomposite films were irradiated with several doses of gamma-ray, ranging from 10-90 kGy. The unirradiated/irradiated nanocomposite films were investigated using FTIR spectroscopy, scanning electron microscope (SEM), roughness testing, UV-Vis spectroscopy, refractometry, densitometry, and photoluminescence spectroscopy. The results were then compared to the pure PVA polymer. FTIR spectra showed a decrease in intensity and a broadening of absorption bands due to interactions between the host PVA polymer atoms/molecules and the TiO2 NPs. SEM showed homogeneous dispersion of the TiO2 NPs in the PVA matrix. Gamma irradiation resulted in more significant morphological alterations and changing the roughness characteristics, the magnitude of which depended on the dose. UV-vis spectra showed the absorption edge significantly changing with increasing gamma doses. The optical energy gap band, Urbach's energy, and the number of carbon clusters of the PVA/TiO2 nanocomposite films before and after gamma radiation were changed in comparison to the pure PVA sample. The refractive index and optical density improved due to the addition of TiO2 and gamma-irradiation. The photoluminescence emission results emphasized the PVA/TiO2 film's high sensitivity to gamma-rays, especially at high doses, resulting in strong fluorescence peaks due to increased defects in the irradiated films. All in all, the results prove that there are alterations in the PVA polymer after the addition of TiO2 and gamma-irradiation, making these films good candidates for a variety of industrial applications, including gamma-ray dosimeters.