NUCLEAR MAGNETIC-RELAXATION STUDY OF POLY(ETHYLENE OXIDE) COMPLEXED WITH LITHIUM TRIFLUOROMETHANESULFONATE

A F-19 and H-1 NMR spin-lattice relaxation investigation of two PEO-LI CF(3)SO(3) samples, with molar ratios O:Li of 3.5:1 and 9:1, in the te mperature range 190-330 K is reported. The F-19 NMR measurements form the main focus of the study and these are shown to reflect the propert ies of the single crystalline complex which is known to be present in PEO-LICF(3)SO(3) mixtures. A F-19 relaxation model is developed in whi ch the motion of the CF3 groups about their threefold axes gives rise to an intramolecular dipolar mechanism but in addition there is a cont ribution from heteronuclear dipolar interactions between the CF3 group s of the CF3SO3- anions and the CH2 groups of the polymer chain. The s imulation of the observed experimental spin-lattice relaxation behavio ur is based upon a detailed discussion of the properties of a F-19, H- 1 model system and involves the analysis of reduced second moment rati os. It is suggested that this type of approach has general applicabili ty in cases where a detailed motional model is not available. Reasonab le agreement is found between the simulated and experimental relaxatio n behaviour.