pH-Responsive Self-Healing Anticorrosion Coating Based on a Lignin Microsphere Encapsulating Inhibitor

In this work, we offered a facile strategy to produce lignin microspheres (LMS) with loading of benzotriazole (BTA) inhibitors, which were released as the pH changed. The morphological and compositional characterizations demonstrated that the BTA inhibitors were efficiently encapsulated in the LMS whose load was up to 15.5 wt %. Tests of crossed scratches of coatings indicated that the LMS@BTA/pure waterborne epoxy resin (WEP) had a good self-healing property. By the electrochemical impedance spectroscopy test, the long-term anticorrosion property of LMS@BTA/WEP composites was 1 order of magnitude higher than that of WEP, which indicated that LMS@BTA greatly improved the corrosion resistance. The highly effective anticorrosion should be attributed to the pH-responsive release behavior of BTA from LMS, which actively protected the steel substrate. The enhanced anticorrosion and the controlled release of BTA enlarged the high value-added applications of lignin.