An infrared study of water in perfluorosulfonate (Nafion) membranes

Abstract

MICHAEL FALK. Can. J. Chem. 58, 1495 (1980). We have studied the infrared spectra of H 2 0 , D20, and HDO in hydrated Nafion membranes in the sodium form. The spectrum of isotopically isolated HDO exhibits two distinct absorption bands in the OH stretching region and similarly in the OD stretching region. These bands have been taken to correspond to two distinct environments of the OH groups in Nafion, identified as 0-H..O and 0-H...CF , . It appears that a substantial proportion of water molecules have an OH group (or occasionally both OH groups) exposed to the fluorocarbon environment. This implies that the hydrated ion clusters are either much smaller than previously estimated or, more likely, are non-spherical in shape with frequent local intrusions of the fluorocarbon phase. Water in Nafion is much less strongly hydrogen-bonded than water in aqueous salt solutions at the same temperature and may be expected to have distinct physical properties.

Detection of Ni2+ by a Dimethylglyoxime Probe Using Attenuated Total-Reflection Infrared Spectroscopy

“…However, there was a slight overlap of a Nafion peak (i.e. solvated SO3 -group in the 1600 -1650 cm -1 ) 18,19 with that of the C=N peak from Ni(DMG)2. The results suggest that Nafion film aids in holding the DMG probe molecule onto to the silicon ATR element, and could be used as a matrix.…”

“…The IR spectrum of Nafion has been wellstudied. [18][19][20] In addition, the cation exchange properties of Nafion membranes should assist in transporting Ni 2+ ions into the matrix to interact more efficiently with the DMG probe molecule. Figure 2(c) shows an ex situ MIRIS spectrum of a DMG/Nafion-coated ATR element after being immersed in a 50 ppm Ni 2+ solution.…”

SANS Study of the Effects of Water Vapor Sorption on the Nanoscale Structure of Perfluorinated Sulfonic Acid (NAFION) Membranes

“…18,19 Water dynamics in the PFSA membrane have been studied with quasielastic neutron scattering (QENS). 20 Infrared spectroscopy for studying the water and ionic domain interaction 2,[21][22][23][24] and nuclear magnetic resonance (NMR) for studying nuclear dipole-dipole relaxation or chemical structure analysis [25][26][27] have also been used. In parallel with experiments, simulations of structure reconstruction from SAXS, 28 the chain conformation in a solvent, 29 the effect of the polar side chain distribution on the backbone, 30 and the aggregation of the ionic domains with water 31 have been performed.…”

Propriedades físico-químicas relacionadas ao desenvolvimento de membranas de Nafion® para aplicações em células a combustível do tipo PEMFC

“…Nesse modelo, conhecido como modelo de Yeager, a microestrutura do Nafion ® é tratada como um sistema de três fases: I) fase de fluorocarbonos parcialmente na forma microcristalina; II) uma região intermediária entre as fases I e III, constituída de cadeias laterais pendentes e pequenas frações de grupos -SO 3 -que não participam dos clusters iônicos, água adsorvida e contra-íons [36][37][38][39] ; e III) clusters iônicos formados pelos grupos -SO 3 -e alguns contra-íons. Independentemente, Sakai e Ogumi mostraram que a permeabilidade gasosa ocorre por um mecanismo cooperativo entre a difusão no meio aquoso (fase III) e na matriz hidrofóbica constituída pela fase II no modelo de Yeager [36,37] .…”