Conducting polymer/bio‐material composite coatings for corrosion protection

Abstract

Present study demonstrates a facile in situ oxidative copolymerization method to synthesize conducting copolymer composites in aqueous chitosan medium. The development of poly(aniline‐co‐o‐toluidine)–chitosan–SiO2/epoxy composite coatings were carried out by thermal curing of the spray‐coated mild steel substrates. FT‐IR analysis, XRD studies, SEM and HR‐TEM evidenced that the composite has synergistically integrated properties of the copolymer and the SiO2 nanoparticles. The electrochemical analyses of the coatings in 3.5% NaCl solution manifest an efficient role of copolymer composite in the remarkable improvement of the corrosion resistance of the substrate. The analyses involve Tafel polarization and electrochemical impedance spectroscopy (EIS) studies. The corrosion inhibition property of conducting copolymers, the film forming ability of chitosan, and robustness of SiO2 nanoparticles kept the corrosion rate of the coatings significantly low, under highly corrosive conditions. Mild steel coated with 3.0% loading of copolymer composite coating demonstrated very low corrosion current density (icorr) and significantly high pore resistance (Rpore).

o-Toluidine in electrochemistry – an overview

“…Such copolymer coating with TiO 2 instead of flash has been examined [122]. A similar composite of such copolymer with chitosan and SiO 2 has been examined; the same question regarding o-toluidine remains [123]. 99.52% protection efficiency was noted, still inferior to a coating using 2,3-xylidine instead of o-toluidine.…”

Corrosion protection of stainless steel by a new and low‐cost organic coating obtained from cashew nutshell liquid

“…However, they present limitations that difficult their application and create challenges to their morphology that need to be developed to achieve better and stable anticorrosive properties. The literature 4,13–15 presents several composites and blends that can be used to improve some assets of coatings applied for corrosion protection purposes 16,17 . Part of the organic coatings are produced by electrosynthesis on the active metallic surface via monomer oxidation, driven by the addition polymerization mechanism, such as polyaniline and polypyrrole 18,19 …”

“…The t‐CNSL is obtained from the hot route when the chestnut shell is processed (hot extraction) as an industry subproduct. The t‐CNSL is constituted of between 60%–94% cardanol 14,16,17,28,29 …”

Studies on coatings containing nano‐zinc oxide for steel protection

“…It is very important to protect metals and alloys from corrosion by organic coating. [1][2][3] Polyurethane (PU) and epoxy coatings are highly resistant to abrasion and corrosion and have good adhesion to substrates. PU is also widely used in the manufacturing and defense industries.…”