THE ROLE OF IONIC SALTS IN DETERMINING T-G AND IONIC-CONDUCTIVITY IN CONCENTRATED PEG ELECTROLYTE-SOLUTIONS

The glass transition temperature, T-g, and ionic conductivity, sigma, have been measured for mixtures of low molecular weight poly(ethylene glycol)s with LiCF3SO3, LiClO4, NaClO4, LiBF4 and NaBF4. The variation of sigma with temperature T has been fitted to the Vogel-Tammann-Fulcher (VTF) equation, sigma = AT(-1/2) exp[-B/(T - T-0)] (where A is a pre-exponential factor, B is an apparent activation energy and T-0 is the ideal glass transition temperature). It is found that both T-g and B are dependent on the anion but not the cation, that B varies linearly with T-g and that T-0 is independent of salt concentration. These observations are interpreted in terms of the effect of salt on the flexibility of the oxyethylene chain helix.