Electrospun nanofiber enhanced sulfonated poly (phthalazinone ether sulfone ketone) composite proton exchange membranes

A simple method of improving interfacial compatibility of electrospun composite proton exchange membranes is developed by filling interfiber voids of the sulfonated poly (phthalazinone ether sulfone ketone) (SPPESK) electrospun nanofiber mats with SPPESK matrix. Fiberization improves proton conductivity, swelling resistance and mechanical and thermal stabilities of SPPESK materials. TEM and SAXS measurements show larger and ordered ionic clusters aggregated along the interfaces between SPPESK nanofibers and matrix, resulting in as high as 1.3 times of proton conductivity as compared with the cast membranes. The strategy of higher ion exchange capacity (IEC) electrospun fibers with lower IEC interfiber voids filler maximizes contributions of the embedded SPPESK fiber mats. The IEC2.01fiber/IEC1.72filler electrospun membrane exhibits high proton conductivity (186.4 mS cm−1) and controlled swelling ratio (30.0%) at 80 °C, achieving improvements on open circuit voltage and power density in single cell operations as compared with the IEC1.89 cast SPPESK membrane and Nafion 212 membrane.