DYNAMICS IN A POLY(ETHYLENE OXIDE)-BASED NANOCOMPOSITE POLYMER ELECTROLYTE PROBED BY SOLID-STATE NMR

Novel nanocomposite polymer electrolytes have been synthesized by inte rcalation of poly(ethylene oxide) into various layered silicates. In t his work we use solid state NMR to probe dynamics associated with both the cations and the polymer over a broad temperature range. Spin-latt ice relaxation studies reveal the influence of the polymer backbone dy namics on the Li-7(+) T-l, and we discuss why such measurements need t o be interpreted with care. Cation dynamics are separated from that of the polymer by an analysis of the temperature dependence of the Li-7 spectrum in the presence of paramagnetic impurities fixed in the silic ate lattice. The intercalated polymer shows no evidence for either gla ss or melt transitions, and over the same temperature range exhibits t hermally-activated polymer reorientation. Over the same broad temperat ure range, Li+ cations prove to be mobile with the same activation ene rgy. Such measurements appear to indicate that cation diffusion is muc h slower than polymer reorientation in these systems.