Investigation of the geometry and anchoring mode of conducting polythiophene films electrosynthesized on aluminium working electrodes

• Main Authors: El Guerraf, A., Ben Jadi, S., Bouabdallaoui, M., Aouzal, Z., Bazzaoui, M., Aubard, J., Lévi, G., Bazzaoui, E.A.
• Format: Conference Proceeding
• Language: English
• Subjects: Adherence; Electrosynthesis; Polythiophene/aluminium interface; Raman spectroscopy; X-ray photoelectron spectroscopy
• ISSN: 2214-7853; 2214-7853
• DOI: 10.1016/j.matpr.2019.08.084

The mechanism by which an electrochemically synthesized polymeric coating adheres to the surface of the metallic working electrode is complex and poorly known. The determination of the factors responsible for adherence requires a thorough investigation of the interfacial zone. In this context, we have undertaken to analyze by X-ray photoelectron (XPS) and Raman spectroscopies the contact layers of polythiophene with the aluminium working electrode surface. The decomposition of the XPS signals revealed the existence of additional C 1s and S 2p components of low-binding energies, probably due to the establishment of real covalent bonds between the polymer film and the metal substrate, which would explain the strong adherence of polythiophene on aluminium. Moreover, the investigation of the interface PT/Al with Raman spectroscopy has demonstrated the existence, in addition to the normal vibrational modes, of peaks assigned to structural defects in the polymer chains. These defects are close to the surface of the electrode and serve as anchoring sites, thus contributing to the strong adherence of the polymer to the aluminium substrate. Because of the high affinity of aluminium for heteroatoms, it is probable that the plans of the thiophene units are in the “standing” position with the sulfur atoms directed towards the surface of the metal.