Effect of Annealing on Structure and Diffusion in Hydrated Nafion MembranesстатьяИсследовательская статья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 8 января 2021 г.
Аннотация:The annealing of polymer electrolyte membranes isknown to affect the membrane structure and proton conductivity. Theobserved changes depend drastically upon the annealing temperaturesand cooling rates. In this study, we have performed a fully atomisticclassical molecular dynamics simulation of hydrated Nafion at varioushydration levels and annealing rates. The simulations show thecompression of hydrophobic Nafion domains by larger water clusters,with a strong antiplasticization effect upon hydration, demonstrated byincreasing the glass-transition temperature. The close-range proximityof sulfonate−sulfonate groups of Nafion pendant side chains remainsunchanged with the simulated cooling rates. The water clusters inhydrated Nafion become more disconnected and larger in size withslower cooling rates/increased annealing time. This results in thedecrease of water and hydronium diffusivity and the correspondingconductivity, thereby explaining qualitatively the experimental observations.