Electrodeposition of strictly alpha,alpha’-polythiophene chains on oxidizable metals in acidic concentrated aqueous media

Abstract

Electropolymerization of thiophene was performed in aqueous acidic media on various substrates, namely, titanium, nickel and SS steel. The films were successfully elaborated using voltamperometric, chronopotentiometric and chronoamperometric techniques. It was shown that concentrated acids increase the solubility of the monomer, lower its oxidation potential and inhibit the dissolution of the working electrode. Furthermore, the electrosynthesized polythiophene (PT) films are homogeneous and present similar properties to those obtained in organic media. On the other hand, analyses by X-ray photoelectron and infrared spectroscopies indicate the higher oxidation state of the polymers and the contribution of the supporting electrolyte in the doping process. In addition, IR spectra have demonstrated the strictly a, a’ linked polythiophene chains and an estimated degree of polymerization (DP) of about 40. Finally, scanning electron microscopy (SEM) has been used to characterize the morphology of the obtained coating. In this context, the nature of the films depends closely on the type of the electrode, the electrosynthesized mode and the electrolytic medium.