CATALYTIC POLYMERIZATION OF ANILINE AND ITS DERIVATIVES BY USING COPPER(II) SALTS AND OXYGEN - NEW-TYPE OF POLYANILINE WITH BRANCHED STRUCTURE

The catalytic polymerization of aniline and its derivatives was performed by stirring the solution of the corresponding monomer and copper(II) salts (50/5, mmol/mol) in acetonitrile and water (1/1, v/v) under oxygen at room temperature for 24 h. Among copper salts, CuBr2 and CuCl2 are more active than the others. In each case the copper salts do not work as a stoichiometrical oxidant but work as a catalyst, which can be proved on the basis of turn-over-frequency. The polymers isolated were characteristic of polyaniline with an Emeraldine structure, although a small amount of branched structures were by-produced by an addition reaction at ortho-position. Thus, heat treatment of the polymer at 284-degrees-C results in partial decomposition to produce the stable polymer and aniline. Although the resulting polymer had an Emeraldine type structure, a strong doping effect on its electroconductivity was not observed, probably because of the amorphous morphology. The UV-vis spectra of the reaction solution have suggested that the catalytic polymerization of aniline proceeds through the formation of the copper(II) complex of aniline.