Highly charged and stable cross-linked 4,4′-bis(4-aminophenoxy)biphenyl-3,3′-disulfonic acid (BAPBDS)-sulfonated poly(ether sulfone) polymer electrolyte membranes impervious to methanol

Abstract

Disulfonated 4,4′-bis(4-aminophenoxy)biphenyl-3,3′-disulfonic acid (BAPBDS) was synthesized as cross-linking agent. In situ cross-linking of sulfonated poly(ether sulfone) (SPES) via sulfonamide linkage was achieved using BAPBDS, for preparing polymer electrolyte membranes (PEMs), without deterioration in membrane functionality due to cross-linking. Effective cross-linking enhanced the membranes’ dimensional, thermal, and chemical stability without impairing the electro-chemical properties such as ion-exchange capacity and proton conductivity. Thus, the properties of the developed PEMs were significantly improved due to more compact structure of the cross-linked SPES membrane (CPES) over membranes without crosslinking. Comparable selectivity parameter (SP) and direct methanol fuel cell (DMFC) performance of the developed membranes, especially CPES-100, with Nafion 117 (N117) indicated their suitability for fuel cell applications.