Investigation of proton diffusion in Nafion®117 membrane by electrical conductivity and NMR

The proton dynamics in Nafion ®117 is investigated by comparison of the diffusion coefficient DNMR estimated from PFG-NMR with that of Dσ estimated from electrical conductivity. At high water content region, Dσ is about two times higher than DNMR as a result of Grotthuss mechanism. At low water content region, Dσ and DNMR are in good agreement with each other. Both of the diffusion coefficients decrease steeply at low water content region. It can be explained as a result of the percolation transition due to the isolation of ion clusters, which is suggested by the recent small angle X-ray scattering data.