Caracterisation et etude des proprietes electrochimiques et spectroscopiques des polymeres organiques conducteurs conjugues dopage par des metaux de transition d’Oligo et Polyoligothiophenes

Abstract

This work consists of the electrochemical and spectroscopic study of oligothiophenes and their corresponding polymers, modified by complexation or incorporation of metals (Cu, Co and Ag). The modified electrodes electrochemically prepared from oligothiophenes on platinum electrodes, are characterized by cyclic voltammetry (VC), X-ray photoelectron spectroscopy (XPS) and Scanning electron micrograph (SEM). The VC clearly shows the presence of the oxidation and reduction peaks corresponding to the redox of metal after immersion of the modified electrode in a solution containing metals (Cu2+, Co2+ and Ag+). The XPS indicates that the film complexes the metal ion and determines the mode of coordination with the atoms of the film. The complexes chemically prepared from substituted oligothiophenes with the carboxylic groups, are characterized by IR, Raman, VC, XPS and UV-vis. The IR and Raman results show the deprotonation of the OH and its complexation with the metal. The VC was used to analyze the electrochemical behaviour of these materials and to inform us about the possibility or not of the electropolymerisation of the formed complexes. Stability constants of the complexes formed in solution were also calculated. The obtained modified electrodes exhibit interesting electrocatalytic properties towards the oxidation of ascorbic acid, primarily in the case of Ag, where low concentrations of the AA could be detected. The polyoligothiophenes films are also used as anti corrosion coating, the obtained results show that the P3T electrodeposited on steel A304 and A316, reduces the corrosion rate of the latter in two corrosive mediums H2SO4 and NaCl.