Structural and mechanical degradation of polypyrrole films due to aqueous media and heat treatment and the subsequent redoping characteristics

Polypyrrole films doped with p-toluenesulfonate and poly(4-styrenesulfonate) anions were synthesized electrochemically. These films were treated with water and dilute NaOH solution for varying periods of time. The films do not lose the anions readily when treated with water. In NaOH, dedoping occurs rapidly, either via migration of the toluenesulfonate anions out of the film or the neutralization of the poly(4-styrenesulfonate) anions. The undoped polypyrrole is very susceptible to ring oxidation resulting in C-O and C=O groups. Severe deterioration of the mechanical properties of the film also results upon prolonged exposure to NaOH. The effects of heat on the polypyrrole doping level, structure, and mechanical properties were investigated. The results from redoping experiments suggest that unless the dedoping process by NaOH is carried out rapidly, the redoped films will have significantly lower doping levels and conductivities than the pristine films (C) 1997 John Wiley & Sons, Inc.