Refractive index investigation of poly(vinyl alcohol) films with TiO2 nanoparticle inclusions

The refractive index (RI) of polymer nanocomposite of poly(vinyl alcohol) films with TiO2 nanoparticle inclusions with low concentration up to 1.2 wt. % was investigated. Accurate refractometric measurements, by a specially designed laser microrefractometer, were performed at wavelengths 532 and 632.8 nm. The influence of TiO2 concentration on the RI dispersion curves was predicted based on the well-known Sellmeier model. The theoretical analysis, in a small filling factor approximation, was performed, and a relation between the effective RI of the nanocomposite and weight concentrations of the TiO2 nanofiller was derived. The experimental values were approximated by two different functions (linear and a quadratic polynom). The polynomial approximation yields better result, where R-2 = 0.90. (C) 2012 Optical Society of America