Comparative studies of solid-state synthesized polyaniline doped with inorganic acids

Polyaniline (PANI) salts doped with inorganic acids (HCl, H₂SO₄ and H₃PO₄) were directly synthesized by using solid-state polymerization method. The FTIR spectra, UV–vis absorption spectra and X-ray diffraction patterns were used to characterize the molecular structures of the PANI salts. Voltammetric study was done to investigate the electrochemical behaviors of all these PANI salts. The PANI salts were affected by varying the protonation media (HCl, H₂SO₄ and H₃PO₄). The FTIR and UV–vis absorption spectra revealed that all PANI salts contained the conducting emeraldine salt phase at different oxidation state. The crystallinity of PANI doped with HCl was better than those doped with H₂SO₄ and H₃PO₄. The conductivity of the PANI doped with HCl is the highest among the inorganic acid doped PANI.