Nafion/poly(1-vinyl-1,2,4-triazole) blends as proton conducting membranes for polymer electrolyte membrane fuel cells

In this study, proton conducting Nafion-poly(1-vinyl-1,2,4-triazole) blends are produced. Nafion/polymer blend membranes are prepared by means of film casting from the Nafion-PVTri solutions at several molar ratios of PVTri repeat unit to -SO₃H. The chemical structure of the homopolymer PVTri is confirmed by FT-IR and ¹³C NMR. Thermal properties are investigated via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and the results illustrated that all these Nafion-PVTri electrolytes are thermally stable at least up to 300 °C. The membrane properties are further characterized for their morphology by scanning electron microscopy (SEM) and water uptake measurements. The methanol permeability of these membranes is measured and the results exhibited that they have quite lower methanol permeability compared to pristine Nafion112. The electrochemical properties of PVTri are investigated by cyclic voltammetry. The conductivity of Nafion-P(VTri)₁ blend membranes is measured to be 5.3 × 10⁻⁴ S cm⁻¹ at 220 °C, in anhydrous state. The conductivity of blend increased at least three orders of magnitude up on hydration, i.e., exceeding 10⁻³ S cm⁻¹ with RH = 50% at ambient temperature.