Dual sulfonated poly(arylene ether ketone) membrane grafted with 15-crown-5-ether for enhanced proton conductivity and anti-oxidation stability

In the proton exchange membrane fuel cell, durability has recently been the critical issue in its operation. As the Ce3+ cerium ion (Ce) is a potential scavenger for ˙OH and ˙OOH radicals, the main causes of the chemical degradation of the membrane, aminomethyl-15-crown-5-ether (CRE) and dual sulfonated 3,3-diphenylpropylamine (DSDPA) were grafted onto poly(arylene ether ketone) (PAEK) to maintain high proton conductivity and chemical stability by alleviating the migration of Ce from the membrane. The chemical and physical structures of the synthesized CRE-grafted dual sulfonated PAEK membrane (DSPAEK-CRE) along with the coordination complex of CRE and Ce ions were investigated using FT-IR, 1H-NMR and SAXs, and XPS spectroscopy. Fenton's test showed a huge improvement in anti-oxidation stability in the presence of CRE. While the CRE/Ce coordinated membrane showed higher proton conductivity and better chemical stability than the Ce3+ dispersed one, other properties such as water uptake, swelling ratio, and mechanical strength were not significantly affected by CRE.