Anti-corrosion performance of nanostructured poly(aniline-co-metanilic acid) on carbon steel

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• 作者：Cuijuan Xing ; Zhiming Zhang ; Liangmin Yu ; Geoffrey I.N. Waterhouse ; Lijuan Zhang
• 关键词：Poly(aniline-co-metanilic acid) ; Polyaniline ; De-dope ; Corrosion protection ; Carbon steel
• 刊名：Progress in Organic Coatings
• 出版年：February, 2014
• 年：2014
• 卷：77
• 期：2
• 页码：354-360
• 全文大小：2439 K

文摘

In order to investigate the effect of a strongly hydrophilic substituent group on the anticorrosion properties of polyaniline (PANI) coatings, sulfonic acid groups (SO₃H) were introduced into the polyaniline molecular structure by the copolymerization of aniline (ANI) and 3-aminobenzenesulfonic acid (metanilic acid, MA), using ammonium persulfate as an oxidant. The MA/ANI monomer ratio of the poly(aniline-co-metanilic acid) (PANIMA) products was systematically varied in the range 0-1. The PANIMA copolymers contained sulfur in the following forms: HSO₄^{鈭?/sup> from the external dopant (H₂SO₄ obtained from the reduction of the persulfate oxidant) or SO₃H groups from the external MA dopant, and SO₃H groups from the metanilic copolymerization unit. The influence of HSO₄鈭?/sup> or SO₃H in the external dopant and SO₃H in the copolymerization unit on the anticorrosive properties of PANIMA was observed. The morphologies of the different PANIMA products were characterized by SEM. At low MA/ANI ratios, PANIMA nanofibres formed whereas at near stoichiometric MA/ANI ratios PANIMA nanogranules were obtained. The chemical structure of the PANIMA products was determined by FTIR, UV-vis spectroscopy and XRD. The anti-corrosion behavior of PANIMA coated carbon steel electrodes was investigated in 1 M H₂SO₄ solutions by the potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). Results show that the PANIMA coatings offer good anti-corrosion protection to carbon steel in 1 M H₂SO₄ solutions, with the degree of protection depending on the sulfonic acid group and HSO₄鈭?/sup> dopant content in the coatings. Low sulfur content in the PANIMA coatings afforded the best protection, though the performance of all PANIMA coatings was inferior to PANI itself under the applied testing conditions.}