Hydrophobic and self-healing anti-corrosion coatings based on hybrid attapulgite-Ce-MOF pigment

Abstract

This study highlights the combined effect of a 2-methylimidazole cerium-based metal-organic framework (Ce-MOF) developed in situ on attapulgite (ATP) as a nano-hybrid inhibitor pigment (ACE). Hydrolytic condensation impregnated the ACE nanocomposite with a polysiloxane (POS) layer, resulting in the hydrophobic POS@ACE nanocomposite. Immersion studies on AA2024-T3 in a 3.5 wt% NaCl solution with nanocomposite demonstrated an inhibition efficiency (I.E.) of ∼99 %. The novel hydrophobic intelligent polyurethance (PU) coating (PU/POS@ACE) with varied concentrations (1, 3, 5, and 10 wt%) was formulated to examine its anti-corrosion properties. The findings show that after 45 days of electrochemical tests, PU/POS@ACE-10 % maintains the highest |Z|_0.01Hz value of 4.89 GΩ cm² and shows a 375 % increase in |Z|_0.01Hz compared to the blank PU under artificial scratch. This can be attributed to the release of Ce³⁺/Ce⁴⁺, which could generate insoluble passivation films at the alloy/coating interface. The modified coating exhibits substantial hydrophobicity, that ensures long-term anti-corrosion performance. MD-simulation shows strong binding energy (−7.054 eV) between the Ce molecule and Al (111) surface, and the charge distribution profile also shows strong chemisorptive integrity. This study proposes a new design strategy for green Ce-MOF nanocomposites for the development of intelligent protective coatings capable of tolerating distinct service environments.