Graft octa-sulfonated poly(arylene ether) for high performance proton exchange membrane

Abstract

A series of octa-sulfonated poly(arylene ether)s (PAEs) was prepared via a low-temperature grafting reaction and subsequent postsulfonation. The rigid backbone with high molecular weight is conducive to higher integrity of the hydrophobic domain. And the grafting ionic clusters are expected to promote the appearance of phase separation. These membranes, with ion exchange capacity (IEC) values ranging from 1.19 to 1.90 meq. g⁻¹, exhibited excellent dimensional stability, mechanical properties and oxidative stability. The membrane with higher IEC (>1.4 meq. g⁻¹) exhibited adequate conductivity (>100 mS cm⁻¹) in water at 80 °C. Furthermore, the membrane with IEC = 1.90 meq. g⁻¹ exhibited comparable conductivity to Nafion 117 under various humidity levels. In addition, SAXS profiles confirmed the well-defined phase-separated morphology of SPAE-x. DMFC single cell performance demonstrates that SPAE-x are good candidates for proton exchange membranes in fuel cell applications.