Effect of electrolyte on the chemical polymerization of aniline

Chemical syntheses of polyaniline were performed in HCl (0.4–2.51 M) containing 0.1 M aniline and LiCl or MgCl2, keeping the total amount of chloride in the reactional medium constant. This was done in order to investigate if the chloride ion, added as salt and not as acid, is incorporated from chloride containing solutions with lower total acid concentration. The synthesis processes were characterized by potentiometric and calorimetric measurements represented in curves containing kinetic parameters of the polymerization process. The analysis of the polymeric materials was performed by infrared spectroscopy, electric conductivity measurements and scanning electron microscopy. It was observed that both the acid and chloride concentration, have an influence on the polymerization rate and the properties of the polyaniline, however, the presence of monovalent (Li+) or divalent (Mg+2) cations does not seem to have a significant effect. Finally, the conductivity of PAni is lowered by high acid concentrations but high chloride concentrations seem to improve the conductivity.