Fabrication of a proton exchange membrane via blended sulfonimide functionalized polyamide

A novel linear non-fluorinated sulfonimide functionalized polyamide (SPA) polymer electrolyte was successfully synthesized via an aromatic sulfonimide monomer with superior thermal stability and superacidity. The aromatic sulfonimide remains stable below 220 A degrees C. To fabricate membranes with strong mechanical strength and dimensional stability, the polymer was blended with various quantities of PVdF. The PVdF/SPA blend membranes exhibit an excellent capacity of water uptake and high dimensional stability. However, their proton conductivity was found to be substantially lower than that of Nafion 211. Analysis on the SEM images of the PVdF/SPA blend membranes reveals that the low proton conductivity is primarily caused by the large pore structures (> 1 mu m), which lead to breakdown of the continuous proton transport channels.