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

ANDRADA, HEBER E.; FRANZONI, MARÍA; A. C. CARRERAS; VACA CHÁVEZ, F

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2018 vol. 43 p. 8936 - 8943

0360-3199

The dynamics and spatial distribution of water molecules in Nafion 117 membrane has beeninvestigated by 1 H NMR. To this end, 1D and 2D spin-spin (T2 ) relaxometry experiments werecarried out as a function of the relative humidity ranging from 9 to 100%. The inverse Laplacetransform was successfully applied to obtain the 1D T2 distributions and 2D relaxation maps. The1D T2 distributions show two peaks at low RH and mainly one at high water content, which canbe associated with the rearrangement of the exchange sites inside the polymeric channels with theamount of water. From the T2 distribution at 70 % RH three types of water were identified corre-sponding to different degree of molecular mobility. From the 2D T2 -T2 maps molecular exchangebetween the two water populations found at low RH was observed while at 70% the exchangebetween only the two more mobile water populations takes place.