Polyisocyanate bridged hexagonal boron nitride/polyaspartic nanocomposite coatings with superior tribological and anticorrosion performance

The wear resistance of coatings is crucial in a wide range of fields, including automotive, wind power equipment, aerospace, manufacturing, and construction. The development and application of advanced wear and corrosive resistant coatings continue to be a focal point for research and innovation across these industries. Hexagonal boron nitride (h-BN), known for its excellent barrier and self-lubricating characteristics, has demonstrated significant potential in enhancing the anti-corrosion and wear resistance of organic coatings. However, the strong interlayer interactions and inert surface of h-BN result in aggregation within coatings, which weakens interfacial interactions with polymer matrices and thereby limits its application in organic coatings. In this research, we devised a dual-modification strategy, integrating non-covalent and covalent techniques. Polydopamine served as a linking agent, allowing 4,4′-methylenediphenyl diisocyanate (MDI) molecules to be covalently attached to h-BN nanosheets, enhancing both dispersion and interfacial compatibility within high-solid polyaspartic (PAE) coatings. When compared to pure PAE, the MDIBN/PAE composite demonstrated a 10.8 % improvement in tensile strength and a 29.7 % increase in elongation at break. Friction tests further showed a 25.9 % reduction in the friction coefficient and a 40.1 % decrease in wear rate for the MDIBN/PAE composite coating, relative to the pure PAE. After 28 days of immersion in a 3.5 wt% NaCl solution, electrochemical impedance spectroscopy (EIS) indicated a maximum |Z| 0.01Hz of 7.48 × 10 9  Ω·cm 2 , surpassing the pure PAE by 1.5 orders of magnitude. The enhanced performance of the MDIBN/polyaspartic nanocomposite is attributed to the in-situ reaction, ensuring even distribution and excellent compatibility of MDIBN nanosheets within the polyaspartic matrix. This study highlights the potential of this coating for robust anti-corrosion and wear-resistant applications, particularly in metal protection.