Water-borne polyaniline-graft-alkyd for anti-corrosion coating

Water-borne polyaniline grafted alkyd resin (WAR-PANI) anti-corrosion coatings were prepared via the chemical reaction between glycidyl methacrylate (GMA) modified WAR and polyaniline (PANI). The physical blend of PANI and WAR (WAR/PANI) were also prepared for comparison. The obtained WAR-PANI was characterised by fourier transform infrared spectroscopy and transmission electron microscopy. The results show that PANI was successfully grafted onto the chain of WAR. Polarisation tests displayed that the corrosion potential of PANI grafted WAR coating became more positive compared with WAR/PANI physical blend, and the cathodic corrosion was effectively inhibited.

Promising anti-corrosion performance for steel substrate

When the dosage of GMA was 2.67%, the anticorrosion performance of WAR-PANI composite reached the optimum, the corrosion potential shifted from −690 mV to −530 mV, and the corrosion current density decreased from 6.92 × 10−5 to 9.66 × 10−11 A cm2. Electrochemical tests further proved that the impedance modulus and coating resistance of WAR-PANI increased by four orders in comparison with WAR, which were also three orders of magnitude higher than that of WAR/PANI. The surface morphology of the coatings after immersion in 3.5% NaCl solution also demonstrated that the WAR-PANI had good corrosion resistance performance, which displayed much more promising anti-corrosion performance for steel substrate than WAR/PANI physical blend.

The study is published in: Progress in Organic Coatings Volume 126, January 2019, Pages 187-195.