NA-23 NMR EVIDENCE FOR A CHANGE OF DIFFUSION MECHANISM IN NACLO4-POLY(PROPYLENE OXIDE)

Na23 NMR line shapes and spin-lattice relaxation times T1 have been measured for poly(propylene oxide)-NaClO4 complexes. The temperature dependence of T1 exhibits more structure than expected for typical viscous liquid systems, displaying a distinct change in behavior at a temperature Tc1.2Tg at which a minimum in the linewidth also occurs. These observations are interpreted as an indication of a crossover between two distinct dynamical regimes; a regime above Tc where there is a coupling of the ionic motion to the polymer segmental relaxation and a regime below Tc where a decoupling occurs. © 1995 The American Physical Society.