The electropolymerrization of p-phenylenediamine,and the electrocopolymerization between aniline and p-phenylenediamine in 0.5M H2SO4 on ITO electrode was studied was studied in detail by in situ UV-vis spectrometry. It was observed by in situ UV-vis spectrometry the polymerization of p-phenylenediamine and the electrocopolymerization between aniline and p-phenylenediamine happened by cycling potential scan electrolysis. Experimental results showed that the absorbance band at 430nm in in situ UV-Vis spectrum ,the characterization of intermediate during the electropolymerization of aniline, disappeared because of the presence of p-phenylenediamine. It was a direct evidence that indicated the addition of p-phenylenediamine changed the mechanism of the electro-polymerization of aniline on ITO electrode in 0.5M sulfuric acid solution. FTIR spectra of films deposited on ITO electrode was obtained and showed that 1,2 or 1,2,3 substituted modes could exist in the copolymer films. The SEM images of the films showed the additional p-phenylenediamine could changed markedly morphology of films and promoted the growth of fabric morphology with large area. For 20mM aniline+ 2mM PPDA in 0.5M sulfuric acid, the diameter of fiber in film grown on ITO electrode might reach 50nm.The electrochromic behaviors of polymer films were studied in detail. The in situ spectrum of copolymer film deposited on ITO electrode was evidently different from that of polyaniline film on ITO electrode at potential from 0.0v to 0.6v.The electrochromic reversibility of copolymer was better than that of polyaniline. Furthermore, SEM images of polyaniline and copolymer after electrolyzing them at 0.8v for 20 minutes showed aggregation happened on polyaniline granular film and copolymer fibrous film after electrolyzing them at higher potential.

Key words: Aniline, p-phenylenediamine, electrocopolymerization UV-vis spectrometry, FTIR