Autoacceleration/degradation of electrochemical polymerization of substituted anilines

A comparative study was conducted on the kinetic of electropolymerization of ortho, meta and N-alkyl and alkoxy substituted anilines in 1.0 M HCl using cyclic voltammetry. The results show that the net rate of polymer formation was strongly dependent upon the steric hindrance, stability of the radical cations, reactivity of the monomers as well as switch potential. Substituents determine the relative importance of the pathways that lead to formation of polymer or soluble products. The results also indicate that the mutual effect of switch potential on the growth of polymer and its degradation is closely related to the electronic effect of substituent groups. A kinetic expression for the autoacceleration process in the electrochemical polymerization of these aniline derivatives is expressed as ν = k [ p ] n [ M ] n ′ + k ′ [ M ] n ′ − k ″ [ p ] n ″ in which k, k′, [M], [p], and k″ are the initiation (nucleation process) rate constant, the rate constant when the polymer is deposited on the electrode, monomer concentration, the total amount of polymer, and the rate constant of degradation process, respectively.