Polymerization of aniline by copper-catalyzed air oxidation

A novel method for preparing organosoluble and conducting polyaniline (PANI) is presented. It is demonstrated that Cu(II) is an excellent catalyst for the polymerization of aniline by air oxygen in aqueous emulsions. Reactions carried out at 0 °C or at room temperature yield PANIs of reasonably high molecular weights (number-average molecular weight = 23,000-114,000 Da) in an emeraldine base form that are soluble in many organic solvents, such as tetrahydrofuran, dimethylformamide, N-methylpyrrolidinone, chloroform, and acetone. Spectroscopic investigations (ultraviolet, Fourier transform infrared, and ¹H NMR) have shown that PANI obtained by this procedure has the same structure as those prepared by the conventional persulfate oxidation method. The resulting PANIs show reasonable electronic conductivities (0.067-0.320 S cm^-1) upon doping with p-toluenesulfonic acid or dodecyl benzene sulfonic acid.