STUDIES OF WATER IN NAFION MEMBRANES - USING DEUTERON AND O-17 NUCLEAR-MAGNETIC-RESONANCE, AND DIELECTRIC-RELAXATION TECHNIQUES

Deuteron and oxygen-17 nuclear magnetic resonance measurements and die lectric relaxation studies of Nation-117 membranes with variable water content (approximately 5-18% by weight) have been carried out. Glassy behavior of the water domains at low temperature, below ca. 200 K, is evidenced by the specific nature of the H-2 NMR line shapes. Activati on energies extracted from H-2 spin-lattice relaxation data on the hig h temperature side of the T1 minimum exhibit a steady increase with in creasing water content. In spite of a high degree of molecular mobilit y, angular-dependent spectra in both as-received and stretched samples reflect considerable anisotropy of the host polymer. A dielectric los s peak is observed which previously has been attributed to the glass t ransition of the aqueous domains.