Self-diffusion micromechanism in Nafion studied by 2H NMR relaxation dispersionстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 6 октября 2021 г.
Аннотация:Field Cycling (FC) 2H nuclear magnetic resonance (NMR) relaxometry was applied to study dynamics in Nafion NR 212 in the temperaturerange from 300 K to 190 K and water content of λ = 8.2. The sensitive time window of FC was extended up to eight decades using thetemperature–frequency superposition principle and master curve. The rotational correlation times obtained from 2H FC NMR coincide withtranslational correlation times gained from static field 2H NMR diffusometry in the temperature range applied. This fact means that a longrange mass transport in Nafion is coupled to molecular rotations. It is assumed that confined water in Nafion has more ordered oxygensublattices as compared with bulk water, on a short range is similar to ice. We discuss the possible role of D and L defects, typical for theordered ice structure and using this concept to describe the processes of self-diffusion of confined water in Nafion, as well as the similarity of temperature and humidity dependence of self-diffusion and proton conductivity.