One-pot synthesis and construction of a high performance metal-organic structured nano pigment based on nanoceria decorated cerium (III)-imidazole network (NC/CIN) for effective epoxy composite coating anti-corrosion and thermo-mechanical properties improvement

Abstract

For the first time, a novel metal-organic framework (MOF)-like nano-pigment was synthesized for fabrication of a high-performance epoxy composite material with excellent anti-corrosion and thermo-mechanical properties. The nanoceria-decorated cerium (III)-imidazole network (NC/CIN) as a new metal-organic network (MON) structure was produced by a one-pot co-precipitation route through covalent and/or coordinate networking of cerium (III) as metallic cation centers and 2-methylimidazole as organic linker in methanol medium. The NC/CIN structure was analyzed by UV–Visible spectroscopy (UV–Vis), Furrier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), Raman spectroscopy, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) examinations. The characterization results revealed that the thermal-stable CIN hybrid product decorated by ceria nanocrystals (with average particle sizes below 51 nm) was produced via chemical bonding/networking of the cerium and imidazole precursors, resulting in only 0.047 cm3 g−1 pore free volume of the final networked product. Thermo-mechanical and anti-corrosion performance of the NC/CIN-incorporated epoxy composite were examined by tensile, dynamic mechanical thermal analysis (DMTA), electrochemical impedance spectroscopy (EIS) and salt spray evaluations. The results exhibited that the NC/CIN-contained epoxy composite provided remarkable barrier-inhibitive protection for mild steel in the corrosive environment (log |Z|10 mHz = 9.91 Ω cm2 after 7 weeks exposure of the intact coating to saline solution) as well as self-repairing protective properties in the artificial defected nanocomposite. Moreover, the great reinforcement in the cross-linking density (~40.8 mol cm−3, more than 4 times efficiency), ductility and toughness (~246 J, 4 times efficiency) features of the epoxy composite was explored.