THEORETICAL CHARGE AND CONDUCTIVITY STATE-DIAGRAMS FOR POLYANILINE VERSUS POTENTIAL AND PH

According to experimental work, polyaniline (PANi) can exist in several states, which are a function of the acidity level and the potential of the medium. We propose to describe these states as follows: fully reduced and neutralized PANi (NH); the protonated species (NH//2** plus ); the first oxidized neutral and acidified forms, N equals and NH** plus equals ; and finally the fully-oxidized state, which exists in the form N** plus . These forms are in thermodynamic relation to each other according to a classical 'square scheme'. Following several hypotheses concerning the relative thermodynamic potentials and pK values for electron and proton transfers, we present the theoretical potential-pH diagram and a three-dimensional surface diagram for the charge and conductivity of the polymer.