Low methanol permeable crosslinked sulfonated poly(phenylene oxide) membranes with hollow glass microspheres for direct methanol fuel cells

- Crosslinked Sulfonated poly(phenylene oxide) is used as matrix of proton exchange membrane.
- SPPO is introduced onto the surface of hollow glass microsphere via intermolecular interaction.
- Introduced SPPO onto the surface of HGM increase dispersion of HGM in the crosslinked SPPO matrix.
- HGM is used as filler to reduce the methanol permeability.
- Reduced methanol permeability leads to improved selectivity of SPPO membrane.

Organic/inorganic composite membranes based on sulfonated poly(phenylene oxide) (SPPO) and hollow glass microspheres (HGMs) were prepared for use as proton exchange membranes in direct methanol fuel cells (DMFCs). First, SPPO was successfully introduced onto the surfaces of the HGMs (SPPO-HGMs) to increase dispersion of SPPO-HGMs in the SPPO matrix. The SPPO composite membranes were fabricated with varying amounts of SPPO-HGMs. Then the composite SPPO membranes were crosslinked to decrease the methanol permeability and increase the mechanical properties, and the crosslinking time was controlled to determine the optimal crosslinking time. As a result, a 12 h crosslinking time at 80 °C was selected as the optimum. The SPPO-HGM composite membranes exhibited proton conductivities ranging from 0.0294 to 0.0201 S cm−1 and methanol permeability ranging from 5.20 × 10−7 to 1.99 × 10−7 cm2 s−1 at 20 °C.