Azole substituted polyphosphazenes as nonhumidified proton conducting membranes

Abstract

Novel nonhumidified proton conducting membranes have been prepared from the reactions of triazole (Tri) and aminotriazole (Atri) compounds with poly[(4-methylphenoxy) chlorophosphazene] (PMPCP). The composition of the novel polymers (TriP and AtriP) was verified by elemental analysis (EA) and the structure was characterized by FT-IR, H-1 and P-31 NMR. Size exclusion chromatography was used to confirm the polymer formation. Thermogravimetric analysis (TGA) showed that the samples are thermally stable up to approximately 150 degrees C. Differential scanning calorimetry (DSC) results illustrated the homogeneity of the materials. To obtain sufficient proton conductivity at high temperatures in the anhydrous state, the polymers were doped with trifluoromethanesulfonic acid (TA) at various molar ratios, x 0.5, 1, 2 and 3 with respect to the azole unit. The proton conductivity of the polymer electrolytes was measured using high resolution dielectric-impedance analyzer. The proton conductivity of these materials increased with dopant concentration and temperature. Maximum proton conductivity of TriP2TA and AtriP2TA were obtained as 3 x 10(-3) S cm(-1) at 50 degrees C and 0.0412 S cm(-1) at 130 degrees C respectively, in the anhydrous state.