Composite Membrane of Sulfonated Poly (phenylene oxide) Doped with Phosphosilicate Gels for Direct Methanol Fuel Cell

Summary

The newly developed composite membranes of sulfonated poly (phenylene oxide) (SPPO) doped with phosphosilicate gel were prepared for direct methanol fuel cell (DMFC). SPPO with higher ion exchange capacity (IEC) value (IEC=2.83 mequiv./g) was chosen as polymer matrix, and the phosphosilicate gel with P/Si equal to 1.5 was employed as dopant. Sulfonation of PPO was confirmed by FT-IR and ¹H NMR. And the morphology characterization of sol particles with different stirring time was done by TEM. Moreover, the surface morphology of composite membranes was characterized by SEM. As for methanol permeability (P_M) and proton conductivity (σ), it was demonstrated that all composite membranes were displaying lower methanol permeability than Nafion^®112 and comparable conductivity to Nafion^®112 at room temperature under hydration state. When it comes to selectivity parameter (Φ=σ/P_M), composite membranes show higher Φ values than Nafion^®112, and the highest value is 4.70, 5.6 times higher than 0.845 of Nafion^®112. It is implied that the composite membranes will be the promising membrane material used in DMFC.