Quartz crystal microbalance study of electrochemical deposition of poly(3-dodecylthiophene) films on Au electrodes

Poly(3-dodecylthiophene) films were synthesised electrochemically from a pr opylene carbonate solution of the monomer, by galvanostatic method and cycl ic voltammetry. Electrochemical properties of the resulting polymers were c ompared with the properties of regioregular head-to-tail (HT) polymer synth esised chemically. The first part of the work is focused on the electrochem ical characteristics of HT polymer, namely on dependence of the shape of cy clic voltammograms obtained for redox reaction of the polymer on the film t hickness and mean conjugation length. In the second part, the optimum condi tions of electrosynthesis have been established. The quartz crystal microba lance measurements carried out during potentiodynamic polymerisation of 3-d odecylthiophene (by cyclic voltammetry) showed that deposition of the polym er film was preceded by dissolution of the gold substrate. At the later sta ge of the film formation, the oligomers that were initially accumulated in the vicinity of the electrode, attained the crucial lengths and precipitate d on the electrode surface. In the case of a slow diffusion of the monomer to the electrode the growing film may be irreversibly overoxidised or/and c rosslinked. (C) 2000 Elsevier Science Ltd. All rights reserved.