Electropolymerisation of TiO2 polyaniline nanocomposite and its use as a protective coating on mild steel

In this study, TiO2 was used as an additive for polyaniline, considered to be a matrix polymer. The nanocomposite film was fabricated electrochemically on metal surfaces (mild steel and stainless steel). The electrochemical properties of polyaniline could be seen on the cyclic voltammogram.
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Electropolymerisation of TiO2 polyaniline nanocomposite and its use as a protective coating on mild steel JOURNAL OF SCIENCE OF HNUE Interdisciplinary Science, 2013, Vol. 58, No. 5, pp. 22-29 This paper is available online at http://stdb.hnue.edu.vn ELECTROPOLYMERISATION OF TiO2 /POLYANILINE NANOCOMPOSITE AND ITS USE AS A PROTECTIVE COATING ON MILD STEEL Le Minh Duc1 and Vu Quoc Trung2 1 Faculty of Chemistry, University of Technology, Da Nang University of Technology 2 Faculty of Chemistry, Hanoi National University of Education Abstract. Nanocomposite material has been getting much more attention in recent years by scientists. Nanomaterials, which can be used to fabricate nanocomposite, come in the form of wire, tubes or particles. The matrix polymer can be thermoplastics or thermoset plastics such as phenolic resin, epoxy resin, and unsaturated polyester, or conducting polymers such as polyaniline, polypyrrole, polyethylene, polypropylene and polystyrene. In this study, TiO2 was used as an additive for polyaniline, considered to be a matrix polymer. The nanocomposite film was fabricated electrochemically on metal surfaces (mild steel and stainless steel). The electrochemical properties of polyaniline could be seen on the cyclic voltammogram. With mechanical stirring during electropolymerisation, TiO2 nano particles could be incorporated into the nanocomposite film. A TEM image showed that TiO2 particles were distributed homogenously in the coating. The presence of TiO2 also could be seen with X-Ray Diffraction (XRD) measurement. A Scanning Kelvin Probe (SKP) showed that the adhesion and the corrosion resistance of a nanocomposite coating could be improved with TiO2 in a solution of 3% NaCl. Keywords: Nanocomposite, polyaniline, electropolymerisation, corrosion protection, TiO2 , Scanning Kelvin Probe.1. Introduction Nanocomposite material has been getting a lot more attention from scientists inrecent years. Due to its good properties, nanocomposite has been investigated more thanother materials [1, 2]. Nanomaterial consists of at least one constituent that is in the nano meter scale. Itcan be in the form of particle, wire or tube. Because they are so small and on a largeReceived May 20, 2013. Accepted June 25, 2013.Contact Vu Quoc Trung, e-mail address: trungvq@hnue.edu.vn22 Electropolymerisation of TiO2 /polyaniline nanocomposite and its use as a protective coating...specific area, nanomaterials provide very special properties that traditional compositesdo not possess. This suggests that nanomaterial can be used as reinforcement filler innanocomposite, especially to improve the properties of organic coatings. This approachcan be an alternative in the production of organic or nanocomposite coatings. However,there has been little interest in nanocomposite in Vietnam. Nanocomposite can be fabricated based on organic or inorganic matrices. In recentyears, carbon nanotube, Nanowire and TiO2 nanoparticles have served as fillers inthe polymer matrix. Among them, TiO2 drew considerable interest in nanocompositefabrication. TiO2 is a relatively inert, non-toxic and traditional semi-conducting material.TiO2 could enhance the mechanical and optical properties of nanocomposite [3-5]. In principle, polymer matrix can be thermoplastics or thermoset plastics suchas polyethylene, polypropylene, polystyrene or conducting polymer. Depending on theapplication purposes, polymer matrix can be selected. Conducting polymer has been ofinterest in the work of Alan J. Heeger, Alan G. MacDiarmid and Hideki Shirakawa in1976. The 2000 Nobel Prize in Chemistry was awarded jointly to them for the discoveryand development of conductive polymers”. Polyaniline (PANi) can be synthesised eitherby chemical or electrochemical oxidation of monomer aniline. PANi was largely studiedbecause of its metallic behavior, good chemical and thermal stabilities, redox reversibilityand its high electric conductivity when it is doped in an acid media. In addition,polyaniline has been used in some fields of applications such as batteries, protection ofmetals against corrosion and electrocatalysis [1]. In this study, TiO2 /PANi nanocomposite was fabricated electrochemically. TiO2nanoparticles (∼25 nm diameter) were incorporated into nanocomposite film withstirring. The properties of the film were characterized. The anticorrosive ability of thefilm was also tested.2. Content2.1. Experiment In this study, distilled water is used as solvent. The reagents (Aldrich products) weretitanium (IV) oxide (anatase-type TiO2 ) 25 nm rutile powder as a doping semiconductorand aniline with 99.99% purity as a monomer. The supporting electrolyte used is oxalicacid (H2 C2 O4 ) for electropolymerisation of aniline. Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) was done atthe Polymer Laboratory, Ho Chi Minh University of Technology. Electrochemical testswere done in a 3-electrode cell connected to a potentiostat PGS-HH10 (Vietnam). Ag/Galwas a reference electrode and stainless steel was used as a counter electrode. A Scanning Kelvin Probe (SKP) was used at the Max-Planck Institute for Iron,Dusseldorf, Germany. The sample was prepared on mild steel. The delamination 23 Le Minh Duc and Vu Quoc Trungexperiment was carried out in 98% relative humidity and at 25 0 C. A solution of 3%NaCl was used as the medium of delamination. The SKP experiment was arranged as ...