RAMAN-STUDY OF WATER IN NAFION-117 MEMBRANES

We report on a Raman scattering study of the state of water in the aci d form of the perfluorosulfonate exchanger membrane Nafion-117 in H2O- and D2O-wet conditions. The data reveal that in Nafion-117 (molecular weight 1100), as distinct from Nafion with higher molecular weights ( 1200 and 1400), practically all water molecules participate in OH ... H bonding rather than linking to the fluorocarbon matrix. Moreover, th e shifts of the OH and OD bands in Nafion-1100 towards higher frequenc ies as compared to Nafion of larger equivalent weights (1200 and 1400) implies that the state of water in Nafion-117 is more bulk-like than in the higher molecular weight membranes.