Chemical preparation of polyaniline and its derivatives by using cerium(iv) sulfate, and structures of the polymers

Summary form only given. Polyaniline exhibits excellent environmental stability in its electroconducting form. In addition, the redox chemistry of polyaniline makes this polymer suitable for use as a positive electrode in secondary bateries. Polyaniline can be prepared by either an electrochemical or a chemical method. The chemical method is of particular importance because it provides the most feasible route for the production of polyaniline in a large scale. Here, polyaniline and its derivatives were prepared by using cerium(IV) sulfate as an oxidant instead of conventional ammonium persulfate. The effects of the reaction conditions, such as reaction temperature, reaction time, the presence and the concentration of acid, and molar ratio of monomer/oxidant, were investigated to optimize from the viewpoint of electroconductivity and isolated yield. The polyaniline, prepared in neutral medium, exhibits higher electroconductivity and isolated yield than that prepared in acidic medium. In contrast, the latter provides the partial fibrous morphology. It is noteworthy that cerium(IV) sulfate can cause the polymerization of 3,5-xylidine and 2,3-xylidine resulting in the corresponding polymeric products, while no polymeric products can be detected by using the ammonium persulfate as the oxidant. The polymers were characteristic of Emeraldine structures based on the results of IR, UV-Vis, and elemental analysis. The effect of reaction conditions on the morphology of the polymers were discussed on the basis of the results of scanning electron microscope.