Composite Nanofiber Network Membranes for PEM Fuel Cells

A new class of proton-exchange membranes has been developed and characterized, where an interconnected network of proton conducting polymer nanofibers is embedded in an inert (non-conducting) polymer matrix. In the present study the nanofiber network membrane contained electrospun fibers from sulfonated poly(arylene ether sulfone) solutions (with/without sulfonated polyhedral oligomeric silsesquioxane, sPOSS). The membranes were characterized in terms of morphology, proton conductivity, and water uptake. In-plane proton conductivity was measured using a BekkTech cell that was placed in a controlled temperature/humidity chamber. The data show: (1) There was a modest increase in nanofiber> 50%.membrane conductivity when the IEC of the fibers was increased from 2.1 to 2.6 mmol/g (in the absence of sPOSS), (2) There was a substantial increase in membrane conductivity when sPOSS was added to the fibers, and (3) The proton conductivity of the sPOSS-loaded membranes was significantly higher than that for a commercial Nafion 212 sample at 30oC for a relative humidit