Gamma–radiation synthesis and characterization of nanocomposite hydrogels based on poly(vinyl-alcohol)/zirconium NPs/ europium

Abstract

In the present work, nanocomposite hydrogels based on poly(vinyl-alcohol)/zirconium NPs/europium (PVA/ZrO2NPs/Eu3+) hybrid films were prepared by solution casting technique and then exposed to gamma irradiation (0–65 kGy). Zirconium oxide (ZrO2) nanoparticles (NPs) doped with 5mole% Eu3+ were prepared via sol gel technique. The polymer nanocomposite films were characterized by X-ray Diffraction (XRD) analysis, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Furthermore, the PVA/ZrO2/Eu3+ nanocomposites were characterized for their optical properties using UV–Vis–NIR and photoluminescence (PL) spectroscopy. XRD analysis confirms the formation of ZrO2 monoclinic phase with the nanometer size (20 nm–11nm) when the γ-dose increases from 0 to 25 kGy respectively. Phase transition from monoclinic to tetragonal structure with an average particles size about 25 nm was observed when the γ-irradiation dose reaches 35 kGy. Increasing of γ-dose up to 65 kGy, a remarkable decrease in peaks intensity was observed and reappearance of the monoclinic ZrO2 phase again with average particle size about 10 nm. FTIR peaks intensity changes with increasing γ-irradiation doses. SEM observations showed that the nanocomposite film prepared at 35 kGy inhibits the agglomeration of ZrO2:Eu3+ nanoparticles in PVA host. The optical band gap energy decreases with increasing of γ-dose. PL measurements do not show any emission in the nanocomposite up to 25 kGy. However, at 35 kGy the sample exhibits characteristic orange-red emission centered at 607 nm attributed to 5D0→7F2 transition of Eu3+ ions. Further increasing of γ-dose up to 65 kGy, PL peaks intensity decreases drastically.