Developing a dual-functional self-healing nanocomposite utilizing oxidized-multiwall carbon nanotube/highly-porous metal-organic framework (OCNT/ZIF-8) nano-hybrid

In this study, an anticorrosion epoxy (EP) coating based on a nano-hybrid filler of multi-walled carbon nanotubes, and a metal-organic framework (MOF) with mixed active/barrier anticorrosion performance were developed. The nano-hybrid was derived by growing ZIF-8 nanoparticles on an oxidized-multiwall carbon nanotube (OCNT) surface using two distinct synthesis methods, hydrothermal and coprecipitation, denoted as OCNTZ-I and OCNTZ-II, respectively. Different characterization methods proved the successful modification of OCNT structures with ZIF-8 nano-particles. Furthermore, ICP tests confirmed that Zn cations were released more in an acidic medium, showing that the synthesized particles have pH-responsive properties. After the incorporation of the nano-hybrids into EPs, the effectiveness of the nano-hybrids as anticorrosion materials and the effects of the synthesis procedure on nanocomposites performance were examined. EIS measurements, microscopic analyses, and salt spray tests indicated considerable improvements in the active/barrier anticorrosion properties of the nanocomposite EP coatings. After eight weeks of immersion in a saline solution, the OCNTZ-I/EP and OCNTZ-II/EP intact coatings exhibited a high impedance modulus of |Z|10 mHz (over 109 Ω·cm2), which was significantly higher than the control EP. Moreover, following 24 h of immersion, the charge transfer resistance (Rct) of the scratched OCNTZ-I/EP and OCNTZ-II/EP coatings was approximately two and four times higher than the Rct value of the scratched control EP, respectively. Also, the assessments of the adhesion properties of the nanocomposite coatings revealed a significant improvement in adhesion stability. The adhesion loss of the control EP decreased from 86.67% to 38.35% and 41.71% for the OCNTZ-I/EP and OCNTZ-II/EP coatings.