THE GROWTH OF POLYPYRROLE FILMS ON ELECTRODES

The kinetics of growth of polypyrrole films deposited onto electrode surfaces from aqueous solutions of pyrrole have been investigated. The rate-determining step for the growth of the film is the oxidation of pyrrole units or oligomers and their incorporation at the end of polymer chains. In spite of the positive potential imposed on the electrode during electrodeposition, polypyrrole remains essentially in its neutral state during growth and exhibits conductivities which are several orders of magnitude lower than those of already grown films. It is shown that the rate of film growth is limited by the low conductivity of the growing film, which was evaluated from potentiostatic current transients recorded during electrodeposition of polypyrrole.