Possible Repair Mechanism for Hydrocarbon-Based Ionomers Following Damage by Radical Attack

Polymer electrolyte fuel cell (PEFC) membranes are subject to radical-induced degradation. Antioxidant strategies for hydrocarbon-based ionomers containing aromatic units can focus on intermediates that formed upon attack by hydroxyl radicals (HO · ). Among the different intermediates, cation radical P ·+ is most promising target repair, example cerium(III). For “repair” reaction of Ce(III) with a poly( ? -methylstyrene sulfonate) oligomer we determined an activation energy (9 ± 2) kJ mol ?1 and rate constant 1.6 10 8 M s at 80 °C pulse-radiolysis. reduction Ce(IV) hydrogen peroxide was stopped-flow as (30 1) 4.8 6 °C. These parameters fed into kinetics model estimate efficacy cerium (III)/(IV) redox couple catalytic repair agent in membranes. While mitigate polymer degradation, depends degradation pathway nature lifetime intermediates.