Investigation of the electropolymerization of aniline by the in situ techniques of attenuated total reflection (ATR) and external reflection (IRRAS)

Abstract

In situ FTIR spectroscopy has been used to study the structures of the very first polymerization products of aniline and the structural changes of the initial layers during redox processes. In the present study, the techniques of Attenuated Total Reflection (ATR) and IR Reflection Absorption Spectroscopy (IRRAS) have been coupled with electrochemical measurements. The low penetration depth of the IR radiation in the ATR spectroscopy gives rise of structural information of the polymer film at the electrode. The IRRAS technique was used to study the changes of the interface polymer/electrolyte. With ATR spectroscopy spectra of the initial states of potentiodynamic electropolymerization in aqueous solution are presented. The highest polymer growth rate was found during the cathodic scan when radicals are formed by symproportionation of oxidized and reduced dimers. With IRRAS technique structural changes of PANI were observed during oxidation. Pure benzoid ring vibrations decrease and alternating benzoid and quinoid sequences were detected.