Synthesis of polyaniline by using CuCl2 as oxidizing agent

• Aniline can be polymerized to polyaniline by the weak oxidizing agent CuCl2.
• Copper is incorporated in partially oxidized polyaniline as CuCl3− dopant.
• Spectroscopic analysis defines the chemical nature of the polymer and the Cu dopant.
• Negates prior claims that such reactions yield polyaniline/Cu metal composites.

The reaction of aniline with copper(II) chloride in the presence of p-toluene sulfonic acid was investigated. The reactions were carried out in aqueous media for 24 h under a nitrogen atmosphere. The products obtained were characterized by FT-IR, UV–Vis XPS, SEM, N K-edge NEXAFS and CP MAS 13C NMR. Elemental analysis was also carried out to determine the elemental composition of the product. The results showed the presence of partially oxidized, partially protonated polyaniline with [CuCl3]− as the dopant counter ion. A decrease in the final pH and increase in the reaction yield was observed with an increase in the oxidant to monomer ratio. The increase in the yield is due to an increase in the oxidation potential of CuCl2 with an increase in its molar concentration. The low product yields achieved are attributed to the co-formation of a copper(II) chloride aniline coordination complex.

The reaction of aniline with excess copper(II) chloride yields partially oxidized, partially protonated polyaniline with [CuCl3]− as the dopant counter ion.Figure optionsDownload as PowerPoint slide