Flower-Like Covalent Organic Frameworks for Superior Corrosion Resistance and Durability in Epoxy Coatings

Developing high-performance nanocontainers for loading corrosion inhibitors offers a promising approach to addressing metal corrosion. However, the development of a durable material with high loading capacity, controlled release, and active-barrier protection, especially in the long term, remains a challenge. To achieve such properties, both the molecular structure and morphology of the nanocontainers need to be optimized. Herein, a porous, crystalline 3D flower-like covalent organic framework (COF), termed TP-TA COF, constructed from 2D hexagonal nanosheets linked via imine bonds, is reported. Thereafter, through a one-step solvothermal process, the COF is gradually grown on molybdenum disulfide (MDS), forming a layered structure with enhanced porosity to improve barrier properties and facilitate the efficient loading of corrosion inhibitors (zinc cations). The novel MDS-COF-Zn shows a charge transfer resistance of 72 000 Ω.cm² after 24 h and barrier retention for over 3000 h in a 0.6 m saline electrolyte. The MDS-COF-Zn ameliorates the mechanical and weathering properties of epoxy coatings. The adhesion strength of 4.80 MPa and the tensile strength of 46.50 MPa are achieved. Moreover, no color change is observed after 120 h of accelerated weathering testing. Overall, the proposal of novel MDS-COF nanocontainers guides the design for durable hybrid corrosion inhibitors and beyond.