Assessment of the sensitivity of DQF/ZQF 2H NMR of D2O for studying modified nafion membranes at 20 °C and 80 °C

Double and zero quantum filtered (ZQF/DQF) H-2 NMR spectroscopy was used to study D2O in five different Nafion membranes, N117, N115, NR212, XL, and HP, in order to assess the effectiveness of the technique for monitoring differences in thickness, membrane reinforcement, and the addition of chemical stabilizers. Experiments were also carried out at 20 and 80 degrees C to understand if the ZQF/DQF technique could detect changes in the water environments and exchange dynamics as a function of temperature. For two of the membranes, significant decreases in the 1/T-2 relaxation rates were observed at 80 degrees C. The two modified membranes showed changes in the quadrupolar couplings when heated, with the XL membranes showing a drop in the coupling and the HP membranes showing an increase in the coupling. No consistent variations could be associated with thickness, reinforcement or the addition of stabilizers. Overall the technique was able to detect some differences between the membranes but was limited by the variability in the observed NMR data.