Nanofiber network ion-exchange membranes

A three-dimensional interconnected electrospun polyelectrolyte nanofiber network ion-exchange membrane was created and the interfiber viods were filled with an inert/uncharged polymer. A mat of ionomeric nanofibers was electrospun from a solution of 25 wt% of sulfonated poly(arylene ether sulfone) (sPAES) in dimethylacetamide. The volume fraction of fibers and the average fiber diameter increases to 0.73 and 165 nm respectively, with no change in mat thickness. A fiber volume fraction of 1.0 denotes a homogeneous film of 2.5 mmol/g sulfonated sPAES and a volume fraction of 0.0 corresponds to an unchanged NOA63 film. A need for interfiber welding after fiber compactation is confirmed by comparing the in-plane proton conductivity of embedded mats with and without welding. The dependence of water uptake on effective membrane ion-exchange capacity (IEC) is similar to that for a series of homogeneous sPAES films of different IEC.