Nucleation and Growth Mechanism of Electro-synthesized Poly(pyrrole) on Steel

International audiencePolypyrrole was electro-synthetized by potentiodynamic and potentiostatic methods on AISI 316 stainless steel (SS) using lithium perchlorate as supporting electrolyte and acetonitrile as solvent to obtain the respective polymeric coating. One of the most relevant characteristics of this polymer is that its voltammetric response showed the presence of reversible p- and n-doping/undoping processes. Moreover, nucleation and growth mechanisms (NGM) were established by i/t transients deconvolution recorded during the potentiostatic electro-polymerization. It was found that the overall process mechanism involved two contributions, namely an instantaneous nucleation with two-dimensional growth (IN2D) and a three-dimensional progressive nucleation with diffusion-controlled growth (PN3Ddif The nuclei shape predicted by these NGMs are consistent with the respective morphologies obtained by SEM and AFM, which validates, once more, the proposed electro-polymerization model and the predictions from the NGM morphology of the respective electro-deposited polymer. In short, a correlation between the structure of the starting unit, doping and morphology of the electro-deposited polymer was established. At the same time conditions for the electro-obtention of this widely studied polymer were optimized, but this time on SS, a cheap electrodic substrate that makes its potential application more feasible