Polymer Electrolyte Membrane Fuel Cells (PEFMC’s) 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. This work studies the reactivity of the sulfonated PEEK polymer molecule with radicals occurring in operating fuel cells, i.e, H, OH, and OOH radicals.<br/>Reactions of the membrane with these radicals is studied by means of M062X hybrid density functional calculations. The energetics of addition-elimination degradation reactions of these radicals with a sPEEK model molecule are computed in both gas-phase and in a water environment as modeled by polarized continuum model (PCM) calculations. Results for H radicals 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. Similar reactions appear to possible with OH radicals. Reactions with OOH radicals appear to be thermodynamically unfavorable. The impact of solvation and deprotonation of sPEEK on these reactions will be discussed.

Density functional theory investigation of mechanisms of degradation reactions of sulfonated PEEK membranes with H, OH and OOH radicals in fuel cells

2019 Spring National Meeting

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