Ionic conductivity and organisation of macromolecular polyether–alkali-metal salt complexes

Abstract

The ionic association, ionic conductivity and macromolecular organisation of alkali-metal salt complexes with poly(ethylene oxide)(PEO) and related polymers are described. The amorphous phase is the principal pathway for ionic mobility in PEO and two regimes of salt concentration, polymer-rich and salt-rich, may be identified. Most attention so far has been paid to the former, where a better understanding of the state of aggregation of the salt and the mechanism of ion transport are current aims of research. The salt–PEO association gives rise to helical chain conformations in which the cations are enclosed and the anions stack alongside. Extensive macromolecular organisation into domain or fibrous textures may occur in particular systems and the stacking of radical anions such as tetracyanoquinodimethanide form electronically conducting systems. Premelting transformations involving ionic motion in the organised phase give rise to liquid-crystalline behaviour in systems with aromatic anions. The organisation and ionic conductivity of novel smectic liquid-crystalline polymer electrolytes are described.