Single-ion conductivity in comblike polymers

Abstract

We have prepared comblike polymers based on styrene-maleic anhydride and ethylene-maleic anhydride copolymer backbones. Reactions have been carried out in which the cyclic anhydrides were ring opened with the concomitant formation of ester groups on one of the carbonyl functions. The remaining carbonyl group is part of a carboxylic acid. The alcohol moieties are either the monomethyl ethers of triethylene glycol or of polyethylene glycol (MW 350). The resulting polymers were then converted to their lithium salts.

Complex impedance plane measurements of the ionic conductivity in these lithiated polymers have been performed. Cole–Cole plots indicate that there is no electronic contribution to the overall conductivity. The ionic conductivity in the case of the triethylene glycol comb polymer is about 10⁻⁹ S cm⁻¹, whereas that of the polymer with the longer ethylene oxide chain is 10⁻⁷ S cm⁻¹ at room temperature. From the chemical nature of these polymers, it is presumed that all the conductivity is due to the mobility of the Li ion. These data will be compared to the results other laboratories have had with different single-ion conducting polymers.