Polydopamine encapsulates Uio66 loaded with 2-mercaptobenzimidazole composite as intelligent and controllable nanoreservoirs to establish superior active/passive anticorrosion coating

Active protection coatings hold great potential for safeguarding marine engineering equipment by effectively reducing metal corrosion. However, the premature and uncontrollable release of corrosion inhibitors, even in intact coatings, limits their active protection performance. Herein, Uio66 was synthesized to load 2-mercaptobenzimidazole (M), which was further encapsulated with polydopamine (PDA) to produce a Uio66-M-PDA nanomaterial. This composite was then used as a filler to develop anticorrosion waterborne epoxy (Uio66-M-PDA-WEP). Notably, PDA functions as a “faucet”, enabling the efficient storage and controllable release of M molecules. The cross-section morphology indicates that the uniformly distributed Uio66-M-PDA reduces the internal defects and improves the compactness of the coating, which further strengthens the dry (5.23 MPa) and wet (3.65 MPa) adhesion force. Due to the synergistic effect of Uio66, M, and PDA, the resistance value of Uio66-M-PDA-WEP remains 8.3 × 10⁹ Ω·cm² after immersion in neutral salt solution for 60 d, which is 1220.6, 334.7, and 5.3 times higher than that of pure WEP (6.8 × 10⁶ Ω·cm²), Uio66-WEP (2.5 × 10⁷ Ω·cm²), and Uio66-M-WEP (1.6 × 10⁹ Ω·cm²), respectively. Furthermore, Uio66-M-PDA-WEP ensures the efficient storage and intelligent release of corrosion inhibitors, offering reliable active protection properties for the metal substrate. In summary, this work successfully addresses the issues of uncontrolled and premature release of corrosion inhibitors in active/passive protective coatings and offers valuable insights for practical application.