Hydrophobic and chemically bonded BNNSs@PDA/ODA nanosheets to enhance the protective properties of silicone-epoxy coatings on 2024 Al-alloy

In the challenging marine environment, organic coatings often fail to provide long-lasting protection. This study presents a novel approach for synthesizing multifunctional nano-pigments by utilizing hydrophobic and chemically bonded BNNSs@PDA/ODA nanosheets. The synthesis involves anchoring polydopamine (PDA) onto boron nitride nanosheets (BNNSs), followed by grafting octadecyl amine (ODA). This dual modification effectively prevents agglomeration of BNNSs and enhances their adhesion with silicone-epoxy resins at the interface. Comprehensive characterization confirms the successful grafting of ODA onto PDA-modified BN nanosheets, significantly improving the barrier properties of coatings. Remarkably, after immersing in a 3.5 wt% NaCl solution for 75 days, the composite coating BNNSs@PDA/ODA-SE exhibits an impedance modulus (|Z|(0.01Hz)) of 10(10) Omega cm(2) at low frequency, surpassing that of pure SE coating by nearly three orders of magnitude. The superior protective performance of the composite coating can be attributed to the synergistic effect between the physical barrier generated by BNNSs, insoluble complexes formed by Al3+-PDA, and the high hydrophobic surface network provided by ODA.