Dynamics and spatial distribution of water in Nafion 117 membrane investigated by NMR spin-spin relaxation

ANDRADA, HEBER E.; FRANZONI, MARÍA B.; CARRERAS, ALEJO C.; VACA CHÁVEZ, FABIÁN

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2018 vol. 43 p. 8936 - 8943

0360-3199

The dynamics and spatial distribution of water molecules in Nafion 117 membrane hasbeen investigated by 1H NMR. To this end, 1D and 2D spin-spin (T2) relaxometry experimentswere carried out as a function of the relative humidity ranging from 9 to 100%. Theinverse Laplace transform was successfully applied to obtain the 1D T2 distributions and 2Drelaxation maps. The 1D T2 distributions show two peaks at low RH and mainly one at highwater content, which can be associated with the rearrangement of the exchange sitesinside the polymeric channels with the amount of water. From the T2 distribution at 70%RH three types of water were identified corresponding to different degree of molecularmobility. The 2D T2-T2 maps show molecular exchange between the two water populationsfound at low RH, while at 70% the exchange between only the two more mobile waterpopulations takes place.