Anion exchange membranes based on quaternized polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene for direct methanol alkaline fuel cells

A novel anion exchange membrane has been prepared using polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) as a starting material. Chloromethyl groups are first introduced into the SEBS and then converted into the quaternary ammonium groups. The membrane is characterized by Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA). Water uptake, oxidative resistance, ionic conductivity and methanol permeability are measured to evaluate its performance in a direct methanol alkaline fuel cell. The ionic conductivity and permeability of the membrane to methanol was found to increase with temperature. The membrane exhibits an ionic conductivity of 9.37 x 10(-3) S cm(-1) in deionized water at 80 degrees C. For aqueous methanol solutions between 2 and 10 M at 30 degrees C, the methanol permeability was observed to range 2.34-4.45 x 10(-7) cm(2) s(-1). Our novel SEBS membrane also shows high oxidative resistance to Fenton's reagent and good thermal stability under an air atmosphere. (C) 2009 Elsevier B.V. All rights reserved.