Reaction of SO4˙− with an oligomer of poly(sodium styrenesulfonate). Probing the mechanism of damage to fuelcell membranes

文献情報

出版日 2011-06-08

DOI 10.1039/C1CP20499H

インパクトファクター 3.676

著者

Lorenz Gubler, Alexander Wokaun, Willem H. Koppenol

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要旨

Clarification of the mechanism of degradation of model compounds for polymers used in polymer electrolyte fuel cells may identify intermediates that propagate damage; such knowledge can be used to improve the lifetime of fuel cell membranes, a central issue to continued progress in fuel cell technology. In proton-exchange membranes based on poly(styrene sulfonic acid), hydroxycyclohexadienyl radicals are formed after reaction with HO˙ and thought to decay to short-lived radical cations at low pH. To clarify subsequent reactions, we generated radical cations by reaction of SO4˙− with oligomers of poly(styrene sulfonic acid) (MW ≈ 1100 Da). At 295 K, this reaction proceeds with k = (4.5 ± 0.6) × 108 M−1 s−1, both at pH 2.4 and 3.4, and yields benzyl radicals with an estimated yield of ≤60% relative to [SO4˙−]. The radical cation is too short-lived to be observed: based on a benzyl radical yield of 60%, a lower limit of k > 6.8 × 105 s−1 for the intramolecular transformation of the aromatic radical cation of the oligomer to a benzyl radical is deduced. Our results show that formation of the benzyl radical, an important precursor in the breakdown of the polymer, is irreversible.

掲載誌

Physical Chemistry Chemical Physics

CiteScore: 5.5

自己引用率: 10.3%

年間論文数: 3036

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