Preparation and characterization of SMA/S-POSS hybrid membranes for direct methanol fuel cell applications

A novel sulfonated polyhedral oligomeric silsesquioxane(S-POSS) monomer was synthesized successfully in this article. S-POSS acted as a donor of sulfonic acid group and reacted with poly(styrene-comaleic anhydride) (SMA). FT-IR spectroscopy confirmed the modification through introduction of peaks characteristic of ester linkages and carboxylic groups. The SMA/S-POSS hybrid membranes were fabricated from different S-POSS contents. The proton conductivity and methanol permeability of the hybrid membranes were studied with changing S-POSS content from 5wt. % to 30wt. %. It was found that the proton conductivity and the methanol permeability were dependent on the S-POSS content. Both of proton conductivity and methanol permeability properties improve with increasing S-POSS content. The proton conductivities of the hybrid membranes are in the range of 10−3 - 10−2 S μ cm−1, and the range of methanol permeabilities was between 10−8 and 10−7 cm2·s−1. The membranes show good thermal properties characterized by thermogravimetric analysis (TGA).