The chemical and physical properties of pyrrole-based conducting polymers: The oxidation of neutral polypyrrole

Abstract

A series of experiments on the physics and chemistry of polymers derived from pyrroles show that the oxidation of neutral insulating polypyrrole (PP⁰) to its conducting counterpart (PP⁺) is a multistep process. In particular, the conductivity of the polymers increases only in the early stages of oxidation, whereas significant changes in the optical and EPR properties occur in later stages of the oxidation when no further changes in the conductivity take place. The early stages of oxidation lead to an ionic (PP⁺ anion⁻) polymer and the later stages of oxidation result in chemistry at the nitrogen atoms of the pyrrole rings. Similar behavior is observed for all the oxidized pyrrole polymers independent of the method of oxidation.