ZIF-8, a novel lubricant additive, is considered to have great potential in reducing friction and wear due to large specific surface area, thermal stability and mechanical flexibility. However, ZIF-8 nanoparticles readily hydrolyze in aqueous solutions, transforming into large-sized lamellar and rod-like materials, which is a major bottleneck as a water-based lubricant additive. Herein, a strategy is proposed to functionalize ZIF-8 via mussel-inspired polydopamine (PDA) polymerization process to improve its lubrication stability in the water phase. The modified ZIF-8 (PDA@ZIF-8) can firmly “locked” water molecules on the surface of PDA to protect internal structure of ZIF-8, and improve its dispersion and stability of ZIF-8 in water. Moreover, ZIF-8@PDA tribofilm and iron oxide chemical protection film are formed during the friction process, and the low shear strength water layer between the contact surfaces contribute to achieving powerful synergistic lubricating effects, resulting in friction coefficient and wear track width reduce by 65% and 66%, respectively. Therefore, this work provides a promising alternative for expanding the practical application of ZIF-8 in aqueous environment and tribology.

ZIF-8 是一种新型润滑剂添加剂，由于其大比表面积、热稳定性和机械柔韧性，被认为在减少摩擦和磨损方面具有巨大潜力。然而，ZIF-8 纳米粒子在水溶液中很容易水解，转变为大尺寸的层状和棒状材料，这是作为水基润滑剂添加剂的主要瓶颈。在此，提出了一种策略，通过受贻贝启发的聚多巴胺 (PDA) 聚合工艺对 ZIF-8 进行功能化，以提高其在水相中的润滑稳定性。修饰后的ZIF-8（PDA@ZIF-8）可以将水分子牢牢“锁定”在PDA表面，保护ZIF-8的内部结构，提高ZIF-8在水中的分散性和稳定性。此外，在摩擦过程中形成ZIF-8@PDA摩擦膜和氧化铁化学保护膜，接触面之间的低剪切强度水层有助于实现强大的协同润滑效果，使摩擦系数和磨损轨迹宽度分别降低65%和66%。因此，这项工作为扩大 ZIF-8 在水环境和摩擦学中的实际应用提供了一个有希望的替代方案。