Nucleation and growth mechanisms during electropolymerization of substituted 3-alkylthiophenes

In the present work the electrochemical study of compounds based on 3-((ω-bromoalkyloxy) methyl) thiophene, varying the length of the alkyl chain between 6 and 12 carbon atoms, is reported. Electropolymerization of the monomers was achieved by potentiodynamic (cyclic voltammetry, CV) and potentiostatic (constant potential) techniques. Voltammograms obtained by CV show that all monomers can be electrochemically oxidized at potentials about 1800 mV to synthesize the respective polymer. Besides, the potential shifts to more anodic potentials on successive scans, increasing thus the resistivity of the material. Nucleation and growth mechanism (NGM) of electropolymerization was investigated by a potentiostatic technique (j–t). Deconvolution of the current–time transient data fitted with a theoretical model suggests that at short times the instantaneous nucleation with two-dimensional growth (IN2D) contribution prevails, followed by an instantaneous nucleation with three-dimensional growth controlled by the charge transfer (IN3Dct) contribution and, finally at longer times, the instantaneous nucleation with three-dimensional growth controlled by diffusion (IN3Ddif) contribution becomes important. The predominance of each contribution to the NGM depends on the monomer being electropolymerized, and the electrolysis time. The morphology predicted from these NGMs fully correlates with that determined by SEM.