A Comparative Spectroelectrochemical Study of the Redox Electrochemistry of N-(Polyvinylamine)-Substituted-o-Nitroaniline

Abstract

The electrochemistry and spectroelectrochemistry of polyvinylamine (PVAm) and N-(polyvinylamine)-substituted-o-nitroaniline at a polycrystalline gold electrode in contact with different electrolyte solutions (0.1 M HClO4 and 0.1 M KClO4) have been investigated with cyclic voltammetry and surface enhanced Raman spectroscopy (SERS). Cyclic voltammograms recorded with in acidic electrolyte solution showed formation of N-(polyvinylamine)-o-phenylenediamine in the negative going potential scan; in neutral solution reduction proceeds only to N-(polyvinylamine)-o-phenylhydroxylamine. Vibrational modes are discussed and assigned to monomer-surface interactions of adsorbates at the gold surface in both electrolyte solutions. A variety of adsorption behaviors of these polymers at a gold surface is concluded; they apparently depend on the applied electrode potential, pH of electrolyte (acidic or neutral), type and mole percentage of the o-nitroaniline moiety. The adsorption at the gold surface is strongly enhanced with 12.7 mole% of o-nitroaniline moiety, respectively, at its PVAm-backbone. The direct coordination of these polymers with the gold surface occurred via the nitro-group of the o-nitroaniline moiety and primary amino-groups located at the polymer backbone.