Incorporation of a Coumarate Based Corrosion Inhibitor in Waterborne Polymeric Binders for Corrosion Protection Applications

The incorporation of organic corrosion inhibitors into waterborne coatings is optimized in this work. Herein, p-coumaric acid (4-hydroxycinnamic acid) is modified by a butyl radical and its effectiveness as an anticorrosive free inhibitor in solution is confirmed by potentiodynamic polarization (PP). The molecule is then successfully incorporated into waterborne polymeric binders by employing different polymerization techniques in dispersed media. Whenever possible, the inhibitor is also blended into the bare latexes to compare the effect of the incorporating method. The anticorrosion performance of the obtained coatings is tested and compared by electrochemical analysis. Promising results are obtained for the coatings produced by semibatch emulsion polymerization even at the low concentration of 1.5 mg of inhibitor g(-1) latex. The intact control coating without inhibitor shows an impedance of up to 10(6) omega and a phase angle of 72 degrees after 1 h of immersion in the corrosive medium, meanwhile the coating with inhibitor shows higher values, 10(6.7) omega and 80 degrees. Active corrosion inhibition is observed in the coating with inhibitor in which a defect has been done, as the impedances drop to 10(3.9) omega after 24 h of immersion in the saline solution while in the control scratched coating it drops to 10(3.6) omega.