The mechanisms of pyrrole electropolymerization

Over the past twenty years, polypyrrole has appeared as the most extensivel y studied conducting polymer. However, despite the volume of work already d one in this area, there has been little focus put on the mechanism of polyp yrrole synthesis, especially concerning the most efficient method, electrop olymerization. Numerous analytical techniques have been used to study polyp yrrole electrodeposition and/or doping. However, the mechanism itself is st ill a controversial subject as there is not one mechanism which is universa lly accepted. The mechanism proposed by Diaz is the one most commonly refer red to in the literature although several other mechanisms are not lacking in support. The controversy lies in the initiation step as each mechanism p roposes a different way of beginning the reaction, varying between electron transfer, proton transfer and direct radical pyrrole formation. Without co nsidering the initiation step, there are many other factors including elect rolyte, solvent, temperature and pH which can influence the reaction mechan ism during the electropolymerization of pyrrole, thus impacting the charact eristics of the polymer formed at the electrode.