Electrochemical incorporation of copper in polyaniline layers

The electrochemical deposition of copper is studied in polyaniline (PAN) layers with different redox states before the onset of metal deposition. Three characteristic oxidising peaks are found during dissolution of the copper deposit. Their charge contributions depend markedly on both thickness and the redox state of the polymer layers. The combined electrochemical, SEM and XPS studies allow to assign the different dissolution peaks to three types of copper deposits. The most negative peak is ascribed to macrodefects-induced deposition on polymer-free sites on the electrode surface. The middle peak should be connected to copper deposited in/on partially oxidised locations of the PAN coating. The most positive dissolution peak corresponds to copper incorporated in the polymer layer, prone to be dissolved only after driving the polymer layer in its oxidised state. Potentiostatic current transients corresponding to the third type of copper inclusions are studied as a function of deposition potential and PAN layer thickness. The current transients are interpreted by means of a model for instantaneous nucleation and three-dimensional (3D) growth under kinetic control. Data are obtained for the number and size of this type of copper inclusions. (C) 2001 Elsevier Science Ltd. All rights reserved.