Polymer Brush-Functionalized MoS₂ as a Water-Based Lubricant Additive

Water-based lubricants have the advantages of low cost, easy cleaning, and environmental friendliness, and are suitable for various lubrication applications. However, the limited tribological properties of pure water-based lubricants restrict their use. To improve these properties, water-based lubrication additives can be employed. Molybdenum disulfide (MoS₂) is widely used in tribology because of its stability, corrosion resistance, and wear resistance, but it has poor dispersion in water. To address this, MoS₂ functionalized with poly(3-sulfopropyl methacrylate potassium salt) (MoS₂+PSPMA) is successfully prepared by grafting polymer brushes onto MoS₂ using ultraviolet light. The results show that MoS₂+PSPMA exhibits significantly better dispersion stability in water compared to unmodified MoS₂. Additionally, MoS₂+PSPMA demonstrates superior tribological properties as a water-based lubrication additive. During reciprocating friction, MoS₂+PSPMA disperses effectively in water, forming a protective film on the wear surface that reduces friction. As an additive, MoS₂+PSPMA indicates good dispersion and a low friction coefficient in water, positioning it as a promising candidate for future water-based lubricants.