Isotherms of protonation and titration curves of leucoemeraldine and emeraldine

Using the one-dimensional lattice model of polyaniline (PANI) the protonation isotherms of leucoemeraldine and emeraldine have been derived. The interactions between the protons, as well as the presence of the two different kinds of adsorption sites on the PANI chain, have been taken into account. A close agreement between the theoretical and experimental titration curves obtained by Nechtschein and coworkers (Synth. Met., 25 (1988) 311), as well as between both of the protonation isotherms, has been achieved. The difference in energy of the bonds between the proton-amine and proton-imine nitrogen atom has been estimated to be 0.2 eV.