A strategy that combines the adhesion and hydration of polydopamine to realize targeted water lubrication

•A lubrication strategy composed of adhesion and hydration is designed.•Biomimetic adhesion of PDA can realize targeted hydration lubrication.•PDA nanoparticles improve lubricating capacity of water film under load. Water has many natural advantages for using as an ecological lubricant in engineering. However, how to ensure the efficiency and stability of water lubricating film with low viscosity has been always the key point of practical applications. For this, a strategy is given to improve lubricating capacity of water under loads by combining the biomimetic adhesion and hydration lubrication of polydopamine (PDA). The PDA nanoparticles were polymerized and purified, and its aqueous suspensions were used to solve the difficult problem of lubrication failure when using water as lubricant. The morphology characteristics and lubrication performance of PDA nanoparticles were experimentally tested and analyzed. The results showed that PDA nanoparticles can form an adhesive-lubricating film on the copper balls and effectively reduce the tribological behaviors in rubbing processes. This strategy that combines the biomimetic adhesion and hydration lubrication of PDA provides a novel method to realize targeted hydrated film and excellent water lubrication under load bearing conditions.