THE KINETIC-BEHAVIOR FOR THE ELECTROCHEMICAL POLYMERIZATION OF ANILINE IN AQUEOUS-SOLUTION

The electrochemical oxidation of aniline in 0.8 M HCl solution is carr ied out using repeated potential cycling between 0 and 1.1 V (versus S CE). Its anodic peak current at 1.0 V for the first scan is markedly r etarded in the presence of resorcinol or phloroglucinol, and decreases with increasing their concentrations. However, this peak current is s lightly affected by hydroquinone, because it is oxidized electrochemic ally before oxidation of aniline. The experiment of the rotating ring- disk electrode shows that both the disk current at 1.0 V and the ring current for electrolysis of aniline are simultaneously decreased in th e presence of resorcinol. This means that a soluble intermediate catio n generated at the disk electrode is captured by resorcinol. There are four anodic peaks and three reduction peaks on the cyclic voltammogra ms during oxidation of aniline by repeated potential cycling. From the temperature dependence of the separate anodic peak currents, the acti vation energy of each reaction is calculated. For the first scan, the oxidation of aniline at 1.0 V involves two different activation energi es at temperatures from 1 to 35 degrees C. Both activation energies ar e smaller than 21 kJ mol(-1). The values fall into the range of activa tion energies for a general propagation reaction and termination react ion of free radical polymerization. These experimental facts indicate that the initial stage of aniline oxidation is the most likely to invo lve the formation of a radical cation.