LAUSR

Abstract Polyphenols like tannic acid, and others, adsorb spontaneously to the surface of a vast repertoire of materials to coat them with a conformal and functional thin film. Since polyphenols can be oxidized, their deposition can also be controlled at the surface of conductive materials. Since the oxidized form of polyphenols contains reactive quinone groups it could be of interest to electropolymerize them in the presence of nucleophiles, like polyamines to obtain composite coatings with properties different from those displayed by a coating obtained from the polyphenol alone. However in conditions where polyamines are reactive and unprotonated, polyphenols undergo spontaneous, non controlled oxidation. In this article, the electropolymerization of tannic acid (TA) by means of cyclic voltammetry is performed at pH = 5.0. The obtained TA based coatings are compared to those obtained from blends with poly(allylamine hydrochloride) (PAH) as a primary polyamine and with poly(diallyldimethyl ammonium chloride) (PDADMAC) containing quaternary ammonium groups. In these conditions, the polyamines form complexes with TA. It will be shown by means of electrochemical impedance spectroscopy, that the higher the PAH concentration in the blend, the higher is the pseudocapacitance of the film. This finding is explained by the incorporation of positively charged PAH or PDADMAC into the film during the oxidation of TA and by the increase in film roughness/porosity in the presence of the polycation.