Preparation And Anticorrosion Property Of Polyaniline Nanostructures

Based on the self-assembly of nanostructure and the rigid molecular chain of polyaniline, one-dimensional polyaniline nanostructures have been synthesized by interfacial polymerization and direct mixed reaction methods, respectively. The structures and formation mechanism of polyaniline nanostructure have been investigated. Furthermore, the corrosion performance and anticorrosion mechanism of polyaniline nanostructures on steel have been studied. The main results are summarized as follows:1. The direct mixed reaction is a more effective method than interfacial polymerization to synthesize polyaniline nanostructure and can get higher yield ratio. The kinds of doped acid played a major role on morphology and yield of polyaniline.2. High quality polyaniline nanofibers with diameters of 60-100 nm, several micrometers length and conductivity of 6.0 S/cm have been synthesized by direct mixed reaction with aniline and ammonium peroxydisulfate in sulphuric acid system. It was concluded that the polyaniline nanofibers with high conductivity, yield ratio and good morphology could be obtained after 16 h reaction under the conditions of 1 mol/L H2SO4 solution and [ANI]/[APS] being equal to 0.8.3. Polyaniline nanofibers and nanotubes have been prepared by direct mixed reaction with aniline and ammonium peroxydisulfate in acetic acid system. The main influence factor of polyaniline morphology and yield is the ratio of aniline to ammonium peroxydisulfate. With polymerization condition of 1 mol/L acetic acid, 0.2 mol/L aniline, 0.1 mol/L ammonium peroxydisulfate and 24 h reaction, twisted polyaniline nanofibers are formed.4. Electrochemical corrosion measurements results indicated that the polyaniline nanofibers synthesized by direct mixed reaction have more excellent corrosion protection than conventional aggregated polyaniline for mild steel. In general, the emeraldine salt (doped) shows better anticorrosion performance than emeraldine base (undoped) in 3.5% NaCl aqueous solution. The oxide passive film, which is formed by interaction of polyaniline and steel, and pure polyaniline coating film on surface of mild steel all have good anticorrosion properties, but their corrosion protection is short term. To get long term protection of polyaniline, it is necessary to develop a blended coating of conventional coating and polyaniline.