| A novel polymer blend consisting of phenyl-sulfonated poly(2,6 dimethyl-1,4-phenylene oxide), SPPO and poly(vinylidene) fluoride, PVF2, is characterized as a potential membrane for polymer electrolyte membrane fuel cells (PEMFCs). SPPO displayed high proton conductivity (>0.20 Ω−1cm −1), yet swelled excessively in water for use in a PEMFC. Blending with PNT2 significantly reduced water uptake, while retaining high levels of conductivity. The membranes performed well as proton conductors in the PEWC, transporting up to 4 A/cm2. Stability in the fuel cell environment was demonstrated for >300 h at 80°C. NMR analysis of the SPPO/PVF2 membranes after fuel cell operation revealed that the membranes were impartial to the anodic environment, yet prone to oxidation at the cathode.; SPPO was found to have a significant effect on the crystalline properties of PVF2. Specifically, at intermediate compositions (50–70 wt%) SPPO lowered the melting point and crystallinity of the PVF2. Additionally, it appeared to promote a specific polymorph of PVF2. Structural investigations using DSC and SAXS revealed phase separation on a scale >100 Å and an interfacial region of ∼14 Å between the polymers. |
