PHOTON-CORRELATION STUDY OF STRUCTURAL RELAXATIONS IN NACF3SO3 CONTAINING POLYMER ELECTROLYTES

The structural relaxation characteristics of NaCF3SO3 complexed poly (propylene-glycol) (PPG) have been investigated using photon correlation spectroscopy. Addition of NaCF3SO3 to PPG results in a considerable slowing of the relaxation dynamics and a broadening of the width of the observed density correlation function. The relaxation time spectrum provides clear evidence of two relaxation processes separated in time and with a relative strength depending on temperature and concentration of the dopant salt. Both processes are attributed to segmental motions of the polymer chains; the slower relaxation to segments that are transiently crosslinked by the solvated cations; the faster process to motions of 'free' segments away from the crosslinks. The results are discussed in relation to models developed to explain the conductivity mechanism in polymer electrolytes.