THE EFFECT OF SALT CONCENTRATION ON THE PROPERTIES OF POLY[OXYMETHYLENE-OLIGO(OXYETHYLENE)] LICLO(4) POLYMER ELECTROLYTES

The thermal and electrochemical properties of mixtures of poly[oxymethylene-oligo(oxyethylene)] (oxymethylene-linked PEG400) with lithium perchlorate were investigated. The mixtures were essentially non-crystalline at room temperature. Glass transition temperatures were found to increase as the salt concentration was increased, with a linear dependence of 1/T(g) on c. Maximum conductivity at room temperature was 6 X 10(-5) S cm-1 at a salt concentration of 0.7-1.0 mol kg-1 (O/Li = 20-30). The molar conductivity at a given temperature went through a maximum at about 0.5 mol kg-1, but compensation for the effect of local viscosity, based on the WLF-VTF approach, showed that the "iso-viscous" molar conductivity was almost independent of salt concentration.