Polypyrrole overoxidation during its chemical synthesis

Abstract The composition of the synthesis medium was investigated by high-performance liquid chromatography during the chemical polymerization of pyrrole with FeCl 3 in water. It is shown that the polypyrrole is simultaneously degraded during the synthesis in short soluble maleimide molecules. This degradation process may be attributed to the polymer ‘overoxidation’ which is described as a gradual polymer oxidation by water in the presence of FeCl 3 . Such a degradation is strongly enhanced at the beginning of the synthesis and leads to poor conductivity products. Moreover, such a degradation appears to be strongly amplified in low FeCl 3 concentration solutions. Quantitative measurements confirm that polymerization is second-order kinetics with respect to FeCl 3 while overoxidation appears to be only first order. A consistent overoxidation mechanism is discussed.