Cp. Rhodes et al., Studies of cation-anion and cation-polymer association in poly(ethylene oxide): Pb(CF3SO3)(2) complexes, SOL ST ION, 126(3-4), 1999, pp. 251-257
Solid polymer electrolytes consisting of poly(ethylene oxide) (PEO) and Pb(
CF3SO3) were investigated by vibrational (Raman and infrared) and Pb-207 nu
clear magnetic resonance (NMR) spectroscopies. The nu(s)(SO3) symmetric str
etch and delta(CF3) deformation vibrational modes both yield information on
cation-anion association effects, while the CH2 rocking mode is very sensi
tive to cation-polyether oxygen interactions. The free ion concentration de
creases with increasing temperature, as commonly observed for many other po
lymer electrolyte systems. In the present case, the largest decrease occurs
in the temperature interval between 60 degrees and 70 degrees C, coincidin
g with melting of the pure PEO phase in the material. However, significant
changes in polymer segmental conformation are also observed beginning aroun
d 50 degrees C. Both temperature ranges in which the vibrational results ex
hibit large changes (50-60 degrees and 60-70 degrees C) also show substanti
al but separate transformations of the Pb-207 NMR chemical shift interactio
n, which is dominated by cation-oxygen association. Both spectroscopic meth
ods, which are sensitive to dynamic processes occurring on vastly different
time scales, are nevertheless consistent in demonstrating the presence of
at least two steps in the transition between the low temperature, partially
crystalline phase and the high temperature, amorphous phase. (C) 1999 Else
vier Science B.V. All rights reserved.