Density functional theory investigation of mechanisms of degradation reactions of sulfonated PEEK membranes with H radicals in fuel cells: addition-elimination bond-breaking reactions in a model molecule

摘要

Polymer electrolyte membrane fuel cells are expected to continue to play a role in the development of alternative energy sources. Sulfonated polyether (ether) ketone, or sulfonated PEEK (sPEEK), membranes are one possible candidate for fuel cell membranes. In this work, the reactivity of the sPEEK polymer molecule with H radicals is studied by M062X hybrid density functional calculations. The energetics of relevant reaction paths were computed in both gas phase and a water environment as modeled by polarized continuum model calculations. Results suggest a simple degradation process in which the addition of H radicals to aromatic rings within the polymer is followed by bond-breaking processes within the polymer chain.