MRA combined spectroelectrochemical studies on the redox stability of PPy/DS films

Pyrrole was electropolymerized in aqueous sodium dodecyl sulfate (SDS) solu tions and a correlation between the absorbance maximum (lambda(max)) and th e effect of micelle formation was found. The redox stability of the film wa s studied in 0.05 M SDS solution by cyclic spectrovoltammetry. The spectral changes acquired in different potential regions were analyzed by matrix ra nk analysis (MRA) to determine the number of independent absorbing species necessary for the description of the observations. With the extension of th e potential to the more positive region a new oxidation step was obtained, which was connected to structural changes in the film owing to swelling. Sp ectral changes proved that no degradation processes occur in the potential range covered. In the more extended potential region neutral polymeric segm ents are required to reach the quasi-metallic state, and the MRA indicated the necessity to assume the presence of extra species which are connected t o partially hydrated parts of the film. (C) 1999 Elsevier Science S.A. All rights reserved.