Poly(o-aminophenol) Electrosynthesized onto Platinum at Acidic and Neutral pH: Comparative Investigation on the Polymers Characteristics and on Their Inner and Outer Interfaces

摘要

The polymer formed by electrochemical oxidation of o-aminophenol (oAP) on platinum substrates,both in neutral and acidic media, has been characterized. Attention was focussed on the threeconstituent phases: the polymer itself and its inner (metal/polymer) and outer (polymer/electrolyticsolution) interfaces. As well known, poly(o-aminophenol) (PoAP) consistently shows tuneableproperties depending on pH, evidencing a remarkable electroactivity or a strong passivating behaviourif synthesized in acidic and in neutral/basic media, respectively. Although much investigated, a fullunderstanding of the polymerization routes has not yet been reached for either the conducting andinsulating films. To improve this situation studies on PoAP were conducted with a combination oftechniques: Cyclic Voltammetry (CV); X-ray Photoelectron Spectroscopy (XPS); Atomic ForceMicroscopy (AFM); and micro-Raman. It was thus possible to compare compositional andmorphological analyses, highlighting in turn different analytical depths of our PoAP/Pt systems. Theresults here obtained add new information on how to recognize the influence of platinum oxidation andits cleanliness on interface reactions. It was also found that, in order to estimate properly the realstructure of both insulating and conducting PoAP, the presence of oxidized terminal groups and watermolecules strongly bonded along the polymer chains must be taken into account.