Physicochemical Properties of Polyaniline Base and Salt Films

Abstract

Polyaniline base and perchlorate salt films cast from N-methylpyr-rolidinone (NMP) solutions are studied using thermogravimetric analysis, infrared and ultraviolet-visible absorption spectroscopy, and x-ray photoelectron spectroscopy. Both types of films retain a substantial amount of solvent. Although most of the solvent can be removed by washing the films with deionized water, some C1O^? ₄ anions are removed from the salt films as well, resulting in a decrease in conductivity. In the salt films, protonation of the amine units in addition to the imine units can be readily achieved using HC1O₄. Structural modifications of the base films are apparent after one reprotonation/deprotonation cycle. These result in a decrease in the solubility of the film, the extent of which increases with the protonation level. Although NMP is a useful solvent for casting polyaniline salt and base films, both leucoemeraldine and perchloric acid protonated salt undergo degradation in this solvent.