A polyurethane/functionalized reduced graphene oxide coating based on a hybrid cross-linking strategy for marine corrosion protection

Marine power components persistently suffer from multiple corrosion challenges, including electrochemical corrosion, cavitation erosion, and abrasive wear, while conventional protection strategies often fail to achieve synergistic mitigation. Inspired by the hierarchical crosslinking architectures of biological proteins—where sophisticated networks maintain structural integrity and functionality through cooperative interactions—this study innovatively designed a series of polyurethane (PU) composite coatings based on Diels-Alder (DA) dynamic covalent bonds, encompassing dual-, triple-, and multi-crosslinked structures. By systematically optimizing the ratio of dual- to triple-crosslinked networks in the PU matrix, we successfully developed a base material with optimal toughness. Further enhancement was achieved by incorporating multifunctional modified graphene capable of multi-crosslinking, resulting in a hierarchically crosslinked composite coating (M-PU). Electrochemical impedance spectroscopy (EIS) revealed that after 30 days of immersion in 3.5 wt% NaCl solution, M-PU exhibited a three-order-of-magnitude increase in low-frequency impedance modulus (|Z| 0.01 Hz ) compared to the unmodified counterpart, demonstrating exceptional corrosion resistance. More importantly, the hierarchical crosslinking network endowed the material with superior mechanical performance: after 48 h of cavitation erosion testing, M-PU showed a 50.4 % reduction in mass loss, while a 64.6 % decrease was observed following 24 h of tribological wear testing. Mechanistic analysis suggests that the energy dissipation and self-repairing capabilities of the multi-crosslinked structure significantly enhance the coating's durability under harsh corrosive conditions. This study not only provides a novel multifunctional protective solution for marine power components but also establishes a theoretical foundation for the application of dynamically crosslinked materials in extreme environments. • A polyurethane elastomer coating based on a hybrid cross-linking strategy for marine corrosion protection was prepared. • M-PU had excellent electrochemical corrosion resistance. • M-PU had excellent anti-cavitation performance. • M-PU had excellent erosion corrosion resistance. • M-PU exhibited recyclable properties.