Conductivities and viscosities of solutions of Li, Na and K thiocyanates in low-molecular-weight liquid copolymers of ethylene oxide and propylene oxide have been measured. The curves of molar conductance us. c5 show well defined maxima and minima. The conductivity is independent of copolymer molecular weight but is enhanced by raising the EO content of the copolymer. The results are interpreted in terms of a model in which the effects of ion association and re-dissociation play an important role. It is suggested that the characteristic properties of liquid polymer electrolytes can be satisfactorily explained only if the current is largely anionic.

Solutions of alkali metal thiocyanates in liquid copolymers of ethylene oxide and propylene oxide provide a convenient medium for measuring conductivities, viscosities and transport numbers in polymer electrolytes by classical methods. The high value of the anion transport number (typically ca. 0.95) is noteworthy. A model, which emphasises the importance of intramolecular solvation of cations, the effects of ion pairing and redissociation, and the crosslinking action of anions at high salt concentrations, accounts satisfactorily for the properties of these liquid systems.

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