Estudo da corrosão em superfícies metálicas eletrodepositadas com polímeros condutores para revelação de impressões digitais latentes

Abstract

In view of the work already carried out by the research group in the development of new materials and methodologies for application in forensic chemistry aimed at developing latent fingerprints, this work seeks to integrate the group's knowledge with a more in-depth study of the corrosion processes that occur on metallic surfaces electrodeposited with conductive polymers. The electrochemical behavior of these materials was investigated through the study of corrosion potentials, Tafel curves and impedance measurements; considering the lithium perchlorate electrolyte and the aging time variation of the latent fingerprint. The relationship between the composition and aging time of the fingerprint in these corrosion processes was evaluated. The study of this behavior is related to the improvement of the electropolymerization technique applied to the development of latent fingerprints. In this sense, from the electrochemical tests and the visual physical aspect of the surfaces, it was verified the existence of oxidation processes occurring on the metallic surfaces through the alteration of the appearance of the samples due to the formation of corrosion products, proven by the displacements of the corrosion potentials , corrosion rates, polarization resistance, etc. It was also possible to observe the effect of fingerprint and aging time on the evolution of these processes, due to the presence of inorganic salts, especially the chloride ions present in these residues. The electrodeposition of PEDOT resulted in a direction of the oxidation processes to the region between the fingerprint ridges, resulting in an improvement of the fingerprint visualization and in a residual corrosion in these regions, that also allows, a enhancement of the visualization of the pattern of the fingerprint ridges.