Preparation of polydopamine nanoparticles/polyurethane composites for self-targeted transfer of hydration lubrication films underwater†

Water lubrication, a green lubrication solution for underwater equipment, has attracted growing research attention. However, the creation of stable lubricating films in open-water environments remains a stubborn challenge. To address this issue, a facile method was put forward to achieve the self-targeted transfer of hydration lubrication films underwater by preparing the polydopamine nanoparticles (PDA NPs) and PDA NPs/polyurethane (PU) composites. The self-targeted transfer behavior is intrinsically attributed to the adhesive and hydration properties of catechol groups within PDA NPs, the nanoscale PDA NPs and the designed structure of the nanocomposites. Comprehensive topographical and chemical analyses, along with tribological characterization studies, verify the lubrication and anti-wear effects resulting from the self-targeted hydration lubrication of the nanocomposites. This research presents a novel method for enhancing the load-bearing capacity and stability of water lubrication, and demonstrates excellent performance in water-lubricated bearings.