The electrochemical synthesis of polypyrrole at a copper electrode: corrosion protection properties

Abstract

Pyrrole was successfully electropolymerized at a copper electrode in a near neutral sodium oxalate solution to generate a homogeneous and adherent polypyrrole film. The growth of these films was facilitated by the initial oxidation of the copper electrode in the oxalate solution to generate a copper oxalate pseudo-passive layer. This layer was sufficiently protective to inhibit further dissolution of the copper electrode and sufficiently conductive to enable the electropolymerization of pyrrole at the interface, and the generation of an adherent polypyrrole film. These films remained stable and conducting for periods exceeding eight days and exhibited significant corrosion protection properties in acidified and neutral 0.1 mol dm (3 NaCl solutions even on polarization to high anodic potentials. #

Corrosion protection of copper using polypyrrole electrosynthesised from a salicylate solution

“…Again, Q values computed were relatively constant, varying between 4 and 6 mF/cm 2 . These high capacitance values are in good agreement with the charge storage ability typically displayed by polypyrrole films [12,15,[42][43][44].…”

“…For example, in a recent study on the corrosion protection of poly(o-ethylaniline) synthesised on copper, the authors presented results on the negligible influence of the polymer thickness on the corrosion protection performance [11]. This suggests that the corrosion protection properties of the system are determined by the polymer formed at the beginning of the deposition process, which is dense and compact and less porous than the subsequent deposited polymer [12].…”

“…The interference of the ppy electrochemistry with the estimation of the corrosion current has been discussed in various publications [12,14]. In an attempt to reduce the contribution from the polymer a Tafel analysis was performed at a scan rate of 0.166 mV/s for copper and ppy-sal coated copper, as depicted in Fig.…”

“…A number of studies have shown that conducting polymers, such as polyaniline and polypyrrole, are promising candidates for the corrosion protection of oxidisable metals [11][12][13][14][15][16][17][18][19]. Conducting polymers (CPs) are redox-active materials with equilibrium potentials more electropositive than those of the substrate, hence as with chromate, potentially beneficial interactions may occur between CPs and the metal substrate, with a consequent alteration of the corrosion behaviour [18].…”

Polypyrrole Coating on Zinc for Corrosion Prevention of Zinc-coated Steels

“…Other authors also presented the corrosion prevention of stainless steel by PANI coating [2][3][4] as well as PPy coating. 5,6) Since the conducting polymer coatings could be electrochemically formed on various metals, 7,8) they were applied to corrosion prevention of the metals of Cu, 9) Zn, 10) Al, 11) Ti, 12) CuNi. 13) As zinc is one of less noble metals, the oxidative PPy formation may not be easy, because the electrochemical oxidation induces anodic dissolution of zinc before the PPy formation.…”