REDOX PROCESSES IN POLYANILINE THIN-FILM STUDIED BY OPTICAL MULTICHANNEL ANALYSIS

Optical multichannel analysis (OMA) was used to follow the kinetics of colour changes in electrochromic polyaniline film when the latter are polarized in an electrolytic medium at different potentials. These colour changes, which are related to the transition from one polymer form to another, are very fast. OMA also allowed us to obtain an apparent value of the film absorption coefficient. In the investigated range (300-800 nm), several absorption phenomena can be displayed which are characteristic of the different polymer forms. Two electrolytic media (1 M HCl and 1 M H2SO4) were compared to investigate the role played by the size of the inserted counter-ion. The overall results allow us to estimate the practical possibility of using polyaniline in electrochromic devices.