1 research outputs found
Proton diffusion in polyelectrolytes based on hydrogenated polynorbornenes with imide side groups in the repeat unit as determined by NMR and impedance spectroscopies
The conductivity of sulfonated membranes based on hydrogenated polynorbornene functionalized
with dicarboximide side groups, specifically hydrogenated poly(exo,endo-N-phenyl-norbornene-5,6-
dicarboximide), was determined by impedance spectroscopy in the temperature range 10–40 ◦C. Using
Nernst–Planck transport equations, the diffusion coefficient of protons in the membranes was estimated.
The diffusion of protons was also measured by pulsed field gradient (PFG) NMR techniques at several
temperatures. The comparison of the temperature dependence of the diffusion coefficients of protons
obtained by the two techniques suggests that a vehicular type mechanism governs the transport. Solid
state 23Na magic angle spinning (MAS) NMR was used to determine the state of sodium counterions in
membranes equilibrated with 1 M sodium chloride solutions. The spectra exhibit two peaks, one narrow
and another broad, corresponding, respectively, to isolated hydrated sodium ions and clustered sodium
ionsThis work was supported by the Comisión Interministerial
de Ciencia y TecnologÃa (projects: CTQ2005-04710/BQU and
MAT2008-06725-C03-01)Peer reviewe