Quaternized polyepichlorohydrin/PTFE composite anion exchange membranes for direct methanol alkaline fuel cells

Novel composite anion exchange membranes have been prepared using polyepichlorohydrin (PECH) to avoid chloromethylation. PECH is first quaternized with N, N, N′, N′- tetramethyl-1,6-hexane diamine (TMHDA) and then combined with porous polytetrafluoroethylene (PTFE) membranes to form composite anion exchange membranes of quaternized PECH(QPECH)/PTFE. The membranes are characterized via scanning electron microscopy (SEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Water uptake, ionic exchange capacity, ionic conductivity and methanol permeability are measured to evaluate their performance in a direct methanol alkaline fuel cell. SEM results indicate that QPECH has penetrated into the pores of the PTFE membranes. The membranes exhibit high ionic exchange capacity and ionic conductivity. The ionic conductivity is in the range 3.60–6.23 × 10−2 S cm−1 at the temperature range 30–80 °C. The membranes have good thermal stability under an air atmosphere and are stable in basic media with KOH concentration up to 8 M at 30 °C