COMPLEX IMPEDANCE, DSC AND LI-7 NMR-STUDIES OF POLY(PROPYLENE OXIDE) COMPLEXED WITH LIN(SO2CF3)2 AND WITH LIASF6

Complex impedance/electrical conductivity, differential scanning calorimetry and Li-7 nuclear magnetic resonance measurements on poly (propylene oxide) complexed with two lithium salts LiN (SO2CF3)2 and LiAsF6, with compositions of eight ether oxygens per lithium, are reported. Ionic mobility, as probed by NMR linewidth and spin-lattice relaxation measurements, is strongly coupled to polymer segmental motion above T(g). The electrical conductivity for PPO8LiAsF6 is about an order of magnitude smaller than for PPO8LiN (SO2CF3)2. This is a consequence of the higher glass transition temperature for PPO8LiAsF6. The stretched exponential parameter beta(sc), obtained in fits to electric modulus data, was found to be about 0.51 for PPO8LiN(SO2CF3)2 and 0.57 for PPO8LiAsF6.