Electrochemical formation and characterization of copolymers based on N-pyrrole derivatives

Organic coatings based on N-(2-carboxyethyl)pyrrole (PPA) and a butyl ester of PPA (BuOPy) were deposited via electrochemical oxidation. The homo- and copolymers were electropolymerized on glassy carbon and stainless steel in acetonitrile using tetrabutylammonium tetrafluoraborate (Bu₄NF₄B) as the electrolyte. The mechanism of deposition on stainless steel was studied by chronoamperometry and by the tapping and phase angle imaging modes of atomic force microscopy. The electrochemical properties and growth of the films were investigated by cyclic voltammetry. The composition of the copolymers was determined by reflection-absorption Fourier transform infrared spectroscopy. We found that while the hydrophilic monomer PPA undergoes progressive nucleation followed by instantaneous growth the hydrophobic BuOPy nucleates instantaneously. The rate of BuOPy electropolymerization was higher than that of PPA, and the resulting film was thicker yet fluffier. Copolymer films were enriched by BuOPy as compared with the electropolymerization solution, which is attributed to the faster rate of electropolymerization of BuOPy than PPA.