Octadecylamine-functionalized hexagonal boron nitride nanosheets toward highly anti-corrosive epoxy composite coatings

Hexagonal boron nitride (h-BN) nanosheets, known for their high aspect ratio, superior barrier properties and unique electrical insulation properties, hold immense potential for enhancing the anti-corrosion performance of organic coatings. Yet, their tendency to aggregate due to strong interlayer interactions within polymer matrix limits their applicability in anti-corrosion coatings. In this study, we developed a precise functionalization method using highly lipophilic octadecylamine (ODA) molecules, with polydopamine as a bridging agent, to enhance the dispersion and interfacial compatibility of h-BN nanosheets within epoxy (EP) coatings. When incorporated into epoxy coatings, the resulting h-BN@ODA/EP composite coating exhibited a remarkable enhancement in long-term corrosion protection. After a 75-day immersion in 3.5 wt% NaCl solution, the h-BN@ODA1.0/EP/steel system demonstrated the highest |Z|f=0.01Hz value of 1.60 × 1010 Ω cm2, nearly three orders of magnitude higher than that of the EP/steel system, concomitant with minimal observed corrosion. Further, LEIS and salt spray tests further confirmed the exceptional protective capabilities of the h-BN@ODA1.0/EP composite coating, even in the presence of structural damage. These findings validate the exceptional anti-corrosion performance of h-BN@ODA1.0/EP composite coatings, stemming from the multifaceted synergies engendered by the effective interfacial compatibility of h-BN@ODA within EP matrix, well-dispersed and superhydrophobic h-BN@ODA nanosheets induced "labyrinth effect" and repulsive interactions toward corrosive species. This work introduces a novel and high-performance h-BN@ODA/EP composite coating with promising applications in anti-corrosion technologies.