Progress in Organic Coatings 65 (2009) 401–404 Contents lists available at ScienceDirect Progress in Organic Coatings journal homepage: www.elsevier.com/locate/porgcoat Short communication Electrochemical polymerization and initial corrosion properties of polyaniline-benzoate film on aluminum Milica M. Gvozdenovi ´ c, Branimir N. Grgur ∗ Faculty of Technology and Metallurgy, Karnegijeva 4, 11120 Belgrade, Serbia article info Article history: Received 21 March 2008 Received in revised form 19 December 2008 Accepted 23 January 2009 Keywords: Aluminum Corrosion Polyaniline abstract Electrochemical synthesis of polyaniline (PANI) on aluminum electrode from aqueous solution of 0.25 mol dm -3 aniline and 0.2 mol dm -3 sodium benzoate has been investigated under potentiodynamic and galvanostatic conditions. Initial corrosion behavior of aluminum and PANI coated aluminum elec- trode exposed to 3% NaCl has been investigated using electrochemical potentiodynamic and impedance spectroscopy technique (EIS). It was shown that PANI coating initially provide corrosion protection of aluminum, decreasing the corrosion current density at least 15 times. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Due to low cost, lightweight and high mechanical resistance, alu- minum is considered as very important construction metal. In order to improve corrosion resistance, different procedures should be applied, mostly related to the formation of coating systems in which chromium contained primers and pretreatment, as a source of both environmental and health hazard could be replaced using elec- troconducting polymers. Electroconducting polymers (ECP) due to unique electrochemical properties make them useful in the wide range of possible application, like microelectronic, opto- electronic, rechargeable batteries, and active corrosion protection [1–3]. ECP can be obtained using both chemical and electrochemical oxidative polymerization. However, electrochemical synthesis is favorable, permitting synthesis without oxidizing agent followed by doping with organic and inorganic ions in one step. The basic problem related to the electrochemical synthesis of ECP on alu- minum is connected to the fact that during the polymerization two simultaneous processes occur on the anode: electrochemical polymerization and deposition of ECP and passivation of the elec- trode by stable protective oxide [4]. Among large number of ECP, polypyrrole (PPY) and polyaniline (PANI) are the most studied for the purpose of the corrosion protection in general. There are reports on electrochemical synthesis of PPY on aluminum and its alloys [5–9]. There are also lot of studies concerning the use of PANI for the corrosion protection of aluminum and aluminum alloys. Most ∗ Corresponding author. Tel.: +381 113303681; fax: +381 113370387. E-mail address: BNGrgur@tmf.bg.ac.rs (B.N. Grgur). of the studies are dealing with PANI coatings obtained by casting the polymer from the solution. Different forms of PANI were used. For example, PANI in the form of emeraldine salt was investigated for the corrosion protection of Al 3003, Al 2024-T3 alloys [2,10,11]. Emeraldine base was also used on Al 3003 and Al 2024-T3 [10,12] and AA 5182 alloys [13]. Racocot et al. reported corrosion protection of aluminum alloys by double-stranded PANI coating [14]. There are few studies dedicated to direct electrochemical syn- thesis of PANI on aluminum. Eftekary reported electrochemical synthesis of PANI from sulfuric acid and aniline solution on enzyme modified aluminum electrode [15]. Conroy and Breslin [16] electrodeposited PANI on pure aluminum electrode using tosylic acid solution containing aniline. They pointed out strong dependence of applied potential and monomer concentration on electrodeposition process. Huerta-Vilca et al. investigated con- ditions for PANI deposition on aluminum from sulfuric acid solution pretreated with alizarin [17]. Wang and Tan studied electrodeposition process of PANI from tosylic acid solution on cathodically pretreated AA 1100 alloy, using wire beam electrode [18]. Karpagam et al. electrodeposited PANI coating on Al 2024 T6 alloy from oxalic and aniline solution [19]. It can be concluded that there is growing interest in investigation of PANI for the corrosion protection of aluminum and aluminum alloys. The protection of PANI is evident although the role of PANI is still under investigation [2]. In our previous papers it was shown that thin PANI film obtained from benzoate containing solution on mild steel was suitable sub- strate for application of the cataphoretic epoxy coating [20–22]. Hence, the aim of this paper is to present some new findings about electrochemical polymerization of aniline from sodium benzoate solution containing aniline and to investigate initial corrosion prop- erties of such system. 0300-9440/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.porgcoat.2009.01.004