Fe³ ⁺-mediated formation and synergistic mechanism of PDA-Fe³ ⁺-HA ternary composite underwater lubrication film

Water-based lubricants are environmentally sustainable, but their inherently low viscosity is not conducive to the formation of stable lubricating films. To address this challenge, we propose a biomimetic strategy that integrates polydopamine (PDA) adhesion and hyaluronic acid (HA) hydration lubrication via Fe³ ⁺ coordination. The PDA-Fe³ ⁺-HA (PFH) ternary composite was prepared stepwise: Fe³ ⁺ coordinated with PDA catechol groups and interacted with HA chains through ionic crosslinking and chelation, thereby anchoring HA onto PDA. Tribological tests of UHMWPE/tin bronze tribopairs lubricated with the optimal PFH composite (mass ratio) showed that, compared with pure water, the average friction coefficient and wear rate decreased by up to 43.93% and 60.28%, respectively. The lubrication mechanism involves three synergistic effects: (i) Fe³ ⁺-enhanced PDA anchoring forms a stable adhesive layer; (ii) surface-exposed HA chains provide a hydrated low-shear lubrication layer; (iii) Fe³ ⁺ coordination bridges PDA and HA, integrating adhesion and lubrication functions. This bioinspired design offers an eco-friendly lubricant additive strategy. Download: Download high-res image (247KB) Download: Download full-size image