Ion exchange membranes based on vinylphosphonic acid-co-acrylonitrile copolymers for fuel cells

AbstractPoly(vinylphosphonic acid-co-acrylonitrile) with various concentrations of vinylphosphonic acid polymer units were prepared by free radical solution polymerization. The membranes were prepared by casting polymer solutions in N,N′-dimethylformamide and evaporating the solvent. Thermogravimetric analysis showed the stability of prepared membranes up to 175°C, and membranes were stable in oxidative Fenton reagent for 1 h at 70°C. The membranes of polymers containing more than 16 mol% of units with phosphonic acid group swelled excessively in water. The ionic conductivity of membranes increased with the increasing concentration of polymer units with a phosphonic acid group in the polymer chain and with temperature. The conductivity of a membrane with 15.5 mol% of polymer units with a phosphonic acid group was 5.15 S m−1 at 35°C. Membrane containing 15.5 mol% phosphonic acid units in polymer was tested in fuel cell.