A polyaniline based intrinsically conducting coating for corrosion protection of structural steels

Among the various corrosion protection strategies for structural steels, coating techniques provide the most cost‐effective protection and have been used as the primary mode of corrosion protection. Existing coating techniques however have been used mainly for their barrier capability and therefore all have a limited service life due to oxidation aging, electrolytic degradation, or various inadvertent defects and flaws occurred in and after coating applications. This work investigated the anti‐corrosion potential of a π‐conjugated polymer—polyaniline (PANi), which was doped into an intrinsically conducting polymer and then included in a two‐layer coating system as a primer layer. To achieve a long service life, the primer layer was made by mixing the conductive PANi in a waterborne poly‐vinyl butyral solution to provide strong adhesion to steel surface, and then topcoated with a layer of elastomer‐modified polyethylene to obtain extra mechanical and barrier protections. Two ASTM standard tests were conducted to evaluate the corrosion durability and tensile adhesion of the two‐layer system, in which the system demonstrated superior performance. The Scanning Kelvin Probe Force Microscopy (SKPFM) was used to provide the microscopic evidences for the outstanding performance. Microsc. Res. Tech. 76:1186–1195, 2013. © 2013 Wiley Periodicals, Inc.