Effect of thickness, chemical nature of dopants and an alkyl substituent on absorption bands of polyaniline

Abstract

The effect of thickness, an alkyl substituent in the ortho position and the chemical nature of the counterion on the absorption spectra of polyaniline films was studied. Previous work performed using the electrochemical quartz crystal microbalance technique (EQCM) has shown a greater participation of anions in the ionic exchange process when the thickness of the film is increased. This fact was attributed to morphological changes leading to different densities of the polymer film, which was demonstrated by SEM experiments. Changes in absorption spectra provoked by conformational changes due to the presence of a substituent and the effect of the chemical nature of the anions are analyzed for Cl⁻, ClO₄ ⁻ and p-toluene sulfonate (PTS⁻).