Coulombic interaction and charge transfer in polymer electrolytes

Efforts in a number of laboratories have focused on preparation of fully amorphous materials, notably 'Comb polymers' consisting of a highly flexible backbone like polysiloxane or polyphosphazene with short ether side chains capable of binding the cation and therefore stabilizing the complex. (1) In these homogeneous phases, the typical ionic concentrations are from 0.5 to 8.0 molar, with average cation/anion separations ranging from 12 to 6 angstroms. Clearly these conditions are those of a highly concentrated electrolyte. It then becomes of interest, in discussing conduction mechanisms, to distinguish between single ion mobilities and interionic interaction effects that can modify the number of mobile ions. We will attempt to distinguish these effects, to characterize each in simple theoretical terms, and thereby to describe the dominant theoretical constructs that must underlie any proper theory of the conductivity of these polymer materials.