Improvement of proton-exchange membranes based on (1-x)(H3PO2/PVA)-xTiO2

Abstract

Using impedance spectroscopy (IS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and infrared spectroscopy (IR) techniques to study the polymer electrolyte membranes based on poly(vinyl alcohol) (PVA) and hypophosphorous acid (H₃ PO₂) with different titanium oxide nanoparticles (TiO$_2$) concentrations. The polymer systems (1-x)(H₃ PO₂/ PVA) + xTiO₂ were prepared using the sol-casting method and different weight percent of TiO₂, x≤ 10.0%. The DSC results show that the glass transition for molar fraction P/OH = 0.3 appears around 75°C and for the samples doped with TiO₂ around 35°C the melting point for all membranes appear around 175°C. The FTIR spectra show changes in the profiles of the absorption bands with the addition of H₃ PO₂ and the different concentrations of TiO₂. The IS results show dielectric and conductivity relaxations as well as a change in DC ionic conductivity with the TiO$_2$ content. The order of the ionic conductivity is about 10^-2 S/cm for 5.0% of TiO₂. The TGA in the heating run shows water loss that is in agreement with de DC conductivity measurements.