Preparation and characterization of high-durability zwitterionic crosslinked proton exchange membranes

Abstract

The present present paper describes the development of a novel proton exchange membrane comprising a poly (styrene sulfonic acid-co-4-vinylpyridine) copolymer that was crosslinked with a haloalkyl crosslinker through the formation of ionic bonding linkages The nucleophilic substitution of these crosslinked membranes as well as a model reaction between pyridine and 1-bromobutane was confirmed by nuclear magnetic resonance (NMR) Tough and flexible membranes of a high mechanical strength were prepared. They demonstrated very elevated thermal, hydrolytic and oxidative stabilities as compared to other sulfonated polymers. The crosslinked membrane composed of zwitterionic molecules with a crosslinking fraction of 90.3, denoted SP-1, exhibited a proton conductivity of ca 7 1 x 10(-2) S cm(-1) at 30 degrees C under 90% relative humidity; a value comparable to that of Nafion 117 Moreover, the crosslinked SP-1 membrane possessed the highest selectivity for methanol fuel cells (3 38 x 10(5) S cm(-3) s), approximately five times that of Nafion 117. thus implying its potential for practical use in high-energy-density devices (C) 2010 Elsevier B.V All rights reserved.