Self diffusion of water and fluorine ions in anion-exchange polymeric materials (membranes and resin) as determined by pulsed-field gradient nuclear magnetic resonance spectroscopy

摘要

The self diffusion of water, ethanol and fluorine ions was studied by means of pulsed--field gradient nuclear magnetic resonance (PFG-NMR) spectroscopy in anion--exchange materials such as membranes and a resin containing quaternary amines as functional groups. Measurements were carried out with a NMR spectrometer at a frequency of 100 MHz for ~1H and 94.3 MHz for ~19F. The temperature dependence of the diffusion decay components in Fˉ form membranes equilibrated with water or an aqueous solution of NH_4F×HF was studied. The morphology of the transport channels in these materials and relationship between the structure of the membrane transport channels and self -diffusion of water and F ions have been discussed. It was shown that the values of self diffusion of fluorine ions in the membranes as determined by PFG--NMR are in good agreement with those obtained by means of electroconductivity measurements.