The determination of the thickness of electrodeposited polymeric films by AFM and electrochemical techniques

The AFM scratching technique was applied to determine the absolute thickness of the electrodeposited poly o-methoxyaniline films in dependence of an anion type (SO42-, Cl-, ClO4-) and a monomer concentration (0.01-0.06 M). The measured thickness range varies from 10 to 2000 nm in dependence on the anion identity and concentration. The AFM data are compared with the thickness calculated from the oxidation charge coupled to the reaction of leucoemeraldine to emeraldine form of the polymer. The proper way to determine capacitance charge is discussed. The observed excess of charge under CV dependence is explained by the charge required for cross linking of the polymeric chains. The anionic influence on the thickness of electrodeposited films is explained by influence of an anion on film morphology, rather than dependence on the anionic radiuses. The results point out that the determination of the number of electrons taking part in the process studied on the basis of the integration of the current-potential (CV), hence the mechanism of the polymerization and oxidation of the polymeric films might be easily mis-leading only because the capacitance charge of the polymer cannot be appropriate determined. (C) 2011 Elsevier B.V. All rights reserved.