Alkali metal ion conductors based on sulfonated poly(p‐phenylene terephthalamide)

To obtain thermally stable and mechanically strong sodium and lithium conducting polymers, we prepared Na+ and Li+ poly(phenylene terephthalamide sulfonate salts) (MW ∼ 5500). We also synthesized oligo(ethylene oxide) (3, 5, or 7 units of ethylene oxide) substituted ethylene carbonate and poly[oxymethylene‐oligo(oxyethylene)]. These are high boiling point liquids with high dielectric constants as well as metal chelating properties. Polyelectrolyte systems were prepared by mixing Na+ or Li+ poly(phenylene terephthalamide sulfonate) salts with various amounts of modified ethylene carbonate and/or poly[oxymethylene‐oligo(oxyethylene)]. Films (0.1–0.5 mm thick) obtained from the blends were found to have considerable mechanical strength; forming free standing films. The ionic conductivities of the Na+ and Li+ polyelectrolyte systems were 10−6−10−5 S/cm at 25°C. Thermal properties of these blend systems were investigated in detail.