Articles you may be interested inSolid state nuclear magnetic resonance investigation of polymer backbone dynamics in poly(ethylene oxide) based lithium and sodium polyether-ester-sulfonate ionomers J. Chem. Phys. 138, 194907 (2013); 10.1063/1.4804654Nuclear magnetic resonance investigation of dynamics in poly(ethylene oxide)-based lithium polyetherester-sulfonate ionomers A comparison of ion transport in different polyethylene oxide-lithium salt composite electrolytesWe have studied the low-temperature NMR line shape for three nuclei ctH, 7Li, and 19F) in poly(ethylene oxide)-lithium salts (LiCI0 4 , LiBF4' and LiAsF 6 ) solid polymer ionic conductors and measured their spin-lattice relaxation rates as functions of frequency and temperature. The three nuclei probe the dynamics of the polymer segments, the cations, and the anions. We find that the Li + cations follow the segmental motion of the chain, while the anions move independently. Homonuclear interactions and heteronuclear interactions with the polymer and the anion contribute to the 7Li line shape. When the heteronuclear contributions were selectively eliminated by the decoupling method, it was found that the Li-H interaction accounts for 80%-90% of the linewidth. Additional evidence for the correlation between the cationic and the polymeric motions is provided by the remarkably similar temperature dependences of the measured relaxation rates for 7Li and lH, which differ significantly from the dependence for 19F. The frequency dependence of the relaxation rates is poorly described by the Bloembergen, Purcell, and Pound model; a recently developed graphical procedure nevertheless shows that the motion of the protons and the anions is governed by a single time scale, while the 7Li ions are affected by an additional scale, associated with the coupling of its quadrupolar moment to the electricfield gradient.
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