Thermal ageing studies of conducting polypyrroles

Conductive polymeric films have been of great interest recently, although one major drawback to their use is environmental stability. Polypyrroles doped with p-toluenesulfonate, tetrafluoroborate and perchlorate anions were examined under elevated temperatures and environments. The use of d.c. electrical conductivity decay measurements and fitting of kinetic models allows changes in bulk properties to be examined. Surface characterisation performed by X-ray photoelectron spectroscopy (XPS) enables detailed investigation into changes in chemical states of surface atoms. The mechanisms described for the change in electrical and structural properties may be attributed to polymer backbone oxidation through free radical oxygen insertion and electrolyte dopant degradation.