Spectrophotometric investigation of CSA-protonated polyaniline solutions and films

Some differences in the UV-Vis-NIR light absorption spectra of camphorsulfonic acid-protonated polyaniline (CSA-PAn) solutions or thin films were observed. They are related to the molecular weight (MW), aggregation state of the polyaniline and to the counteranion nature. High MW polyaniline synthesized at low temperatures gives CSA-PAn films showing an enhanced polaron delocalization. The substitution of the CSA− counteranions by CI− without intermediate deprotonation keeps the polaron delocalization state