A self-healing and anticorrosion epoxy coating based on the novel polymer filler containing a side-linked grafting 2-mercaptobenzothiazole

Abstract

The healing mechanism of traditional self-healing coatings can be divided into “extrinsic” and “intrinsic” types according to the reactants, among which intrinsic restorations can be recycled multiple times and have great potential for applications. But epoxy resin is difficult to achieve intrinsic healing process through secondary bonding and reaction between polymers owing to the high chain rigidity and cross-linking density. In this study, a composite coating combining both “extrinsic” and “intrinsic” healing methods has been fabricated by adding a novel polymer filler (MBT-PGMS), which was synthesized via grafting copolymerization of glycidyl-methacrylate, styrene, methyl-methacrylate and 2-mercaptobenzothiazole (MBT). Multiple analytical techniques have been used to characterize the structure and properties of fillers, and the effect on the anti-corrosion performance and self-healing efficiency of epoxy coatings in 3 wt.% NaCl solution has been studied by electrochemistry measurements and mechanical analysis. Results indicated that the intact coating containing MBT-PGMS (MBT-PGMS/EP) showed prominent corrosion resistance during the immersion of 90 days. Once the coating was scratched, the impedance of MBT-PGMS/EP increased gradually with increasing the immersion time, and reached the optimal performance as the filler amount at 5 wt.%, while the impedance modulus was about 2.8 × 108 Ω cm2 after immersion for 144 h. A dynamic crosslinking model in MBT-PGMS/EP has been proposed to explain the self-healing mechanism.