M. Mortimer et al., NUCLEAR MAGNETIC-RELAXATION STUDY OF POLY(ETHYLENE OXIDE) COMPLEXED WITH LITHIUM TRIFLUOROMETHANESULFONATE, Journal of the Chemical Society. Faraday transactions, 91(17), 1995, pp. 2871-2876
Citations number
28
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
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.