Structural and optical properties of TiO₂ nanoparticles/PVA for different composites thin films

Abstract

Polymeric films based on polyvinyl alcohol (PVA) doped with titanium dioxide nanoparticles at different weight percentage (1.25, 2.5, 5, 7.5, 10 TiO₂/PVA) were prepared using the sonification and casting techniques. The structural properties of amorphous domain in PVA polymer matrix increased with raising the TiO₂ content. The complexation of the dopant with the polymer was examined by FTIR studies .The absorption spectra of UV-Visible light showed irregular changes of the absorption for high doping samples in UV range (7.5, 10 TiO₂ /PVA). Absorbance, transmittance and reflectance spectra were used for the determination of the optical constants. The results indicated that the optical band gap decreases with increasing TiO₂ content, while the refractive index increased to high value for the composites of high dopant. Using the Wemple-DiDomenico model, we calculated the static reflection index, the oscillation energy, and the dispersion energy. The dispersion energy changes slowly as a function of TiO₂ percentage .The dispersion parameters and the high frequency dielectric constant were determined. In addition the average oscillator wavelength λ0 and oscillator strength S0 for the investigated samples were found to be strongly affected by the nanopartices dopant.