Corrosion inhibitor additives are considered to be one of the effective methods to slow down the corrosion of metals, but the corrosion inhibitors will decompose and lose their effect in a long-term corrosive environment. In this work, a smart corrosion inhibitor carrier 2-mercaptobenzimidazole-Zn2+-polydopamine@graphite (MZPG) with excellent pH response was designed and synthesized using a one-pot method. This corrosion inhibitor carrier not only has a very high 2-mercaptobenzimidazole (MBI) loading capacity (38.0%) but also maintains a very low MBI activity to inhibit the decomposition of MZPG in the environment as much as possible. The MZPG/epoxy (MZPG/EP) coatings prepared by the spraying method showed excellent mechanical properties. Electrochemical and salt spray tests showed that the MZPG/EP coatings (1.20 × 1010 Ω·cm2) have excellent corrosion resistance with Rp values up to 3 orders of magnitude higher than that of the EP coating (1.25 × 107 Ω·cm2). Notably, the MZPG/EP coatings maintained good corrosion resistance under acidic conditions due to the pH-responsive release of corrosion inhibitors. This is of great significance for the future development of coatings for highly corrosive environments.
Keywords: 2-mercaptobenzimidazole-Zn2+-polydopamine@graphite; anticorrosion; pH-triggered release; self-healing; smart nanocarrier.