Sulfonated Poly(aryl sulfone)s Containing Ferrous and Ferric Ion Scavenger 1H-Imidazo[4,5-F][1,10]-phenanthroline Groups for Highly Durable Proton Exchange Membranes

Proton exchange membranes prepared from poly(aryl sulfone)s still need to overcome the drawbacks of chemical stability in acidic environments and low electrical conductivity due to water loss at high temperatures. Herein, we synthesized densely sulfonated poly(aryl sulfone) proton exchange membranes containing a 1H-imidazo[4,5-F][1,10]-phenanthroline moiety on the side chain with a metal ion coordination function. The coordination of 1H-imidazo[4,5-F][1,10]-phenanthroline groups to metal ions can effectively prevent the formation of •OH radicals from homolytic cleavage of H2O2 catalyzed by metal ions. Since the conditions for the continuous formation of •OH radicals are fundamentally eliminated, the antioxidant stability of the membrane material is greatly improved. Mesoscale microscopic simulations showed that 1H-imidazo[4,5-F][1,10]-phenanthroline has the effect of inducing phase separation, endowing the proton exchange membrane with a larger hydrophilic structural domain and possibly constructing a better connected channel for proton transport. Notably, these membranes can efficiently capture the Fe2+ and Fe3+ ions to form stable [Fe(phen)3]2+ and [Fe(phen)3]3+ interconnection points, respectively, which could not only enforce the water retention and the mechanical properties of the membranes but also serve as a catalyzed point to prevent H2O2 from undergoing homolytic cleavage and forming •OH radicals.