Application of the Surface Resistance Technique to Study the Metal|Polymer Interface: A Review Article

The use of surface resistance changes as an alternative method to study the metal|polymer interface is reviewed considering both experimental and theoretical aspects. The experimental arrangement in these investigations is, in general, one in which a polymer film is supported on a thin gold film, whose thickness is of the order of the mean free path of the conduction electrons (gold film thickness, φm ∼30 nm). Particular emphasis is laid on the effects of polymer thickness, electrolyte composition, degree of oxidation, and deactivation and reactivation processes of the polymer film on the metal film conductance. Relevant experiments, where the technique was employed to study the redox site distributions at the metal|polymer interface, during oxidation, deactivation and degradation of the polymer, were specially considered. The simple scattering model to explain surface resistance changes of a thin metal film coated with a poly(o-aminophenol) film is outlined on the basis of the specularity parameter, which represents the probability of an electron being reflected specularly or diffusely at the metal film surface. Information obtained by means of surface resistance is compared with that obtained by employing more traditional techniques such as cyclic voltammetry and rotating disc electrode voltammetry.