In Situ UV-Vis Spectroelectrochemical Investigation of the Copolymerization of o-Aminophenol with Aniline

The electrochemical copolymerization of o-aminophenol (OAP) with aniline (AN) in 0.5 mol/L H2SO4 has been investigated using in situ UV-Vis spectroelectrochemisty. The results reveal that OAP can be firstly oxidized to its cation radical, which shows as peak at lambda = 460 nm in the UV-Vis spectra. Then a mixed dimmer intermediate is formed through the cross-reaction of OPA and AN cation radicals with their monomers in solution. The absorpion peak at lambda = 490 nm in the UV-Vis spectra is assigned to this intermediate. The intermediates then react each other to form the oligomer which shows as absorption peak at lambda < 460 nm. On the other hand. the spectroelectrochemical results reveal that OAP can inhibit the polymerization of AN with the increase of the amount of OPA in the mixed solutions.