19F Double Quantum NMR Spectroscopy: A Tool for Probing Dynamics in Proton-Conducting Fluorinated Polymer Materials

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) ²H 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 °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/T₂ relaxation rates were observed at 80 °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.

A magnetic resonance and electrochemical study of the role of polymer mobility in supporting hydrogen transport in perfluorosulfonic acid membranes

Perfluorosulfonic acid (PFSA) materials have been used in polymer electrolyte membrane fuel cells (PEMFCs) as electrolyte materials due to their mechanical durability and high proton conductivity.

Understanding Surface and Interfacial Chemistry in Functional Nanomaterials via Solid-State NMR

Surface and interfacial chemistry is of fundamental importance in functional nanomaterials applied in catalysis, energy storage and conversion, medicine, and other nanotechnologies. It has been a perpetual challenge for the scientific community to get an accurate and comprehensive picture of the structures, dynamics, and interactions at interfaces. Here, some recent examples in the major disciplines of nanomaterials are selected (e.g., nanoporous materials, battery materials, nanocrystals and quantum dots, supramolecular assemblies, drug-delivery systems, ionomers, and graphite oxides) and it is shown how interfacial chemistry can be addressed through the perspective of solid-state NMR characterization techniques.