Synthesis and characterization of a novel proton-exchange membrane for fuel cells operating at high temperatures and low Humidities

The synthesis of a p-toluidine/formalde- hyde (PTF) resin was performed, and the effects of the molar ratio of the individual monomers and the polymer- ization conditions on the structure of the PTF resin were studied. Fourier transform infrared and 13 C-NMR spectra were used to characterize the PTF. Wide-angle X-ray dif- fraction patterns revealed the crystalline structures of vari- ous PTFs. Polarized optical microscopy revealed that the molar ratio of the monomers had a strong effect on the crystalline morphologies. A longer polymerization time turned out a polymer with a higher intrinsic viscosity and molecular weight, which led to differences in the proton conductivity. All of the PTFs showed a higher proton con- ductivity than a commercial Nafion membrane at 90-1008C and 0% relative humidity. The proton conductivity of the PTF series could be improved by sulfonation with sulfuric acid and could be maintained after blending with polyur- ethane. Pure methanol could be used as a fuel source because of the insolubility and nonwetting properties of PTF in methanol to increase the output current density for a PTF membrane electrode assembly. 2007 Wiley Periodi-