Synergistic Tribological Effects of PBMS and Cu NPs via In-Situ Polymerization for Excellent Lubrication and...

Conventional emulsion lubricants typically comprise multiple components to meet requirements such as long-term stability and tribological performance. However, the compositional complexity can pose challenges in preparation, storage, and recycling. To address this issue, the study involved the preparation of a simple acrylic polymer emulsion (termed PBMS) and copper nanoparticles (Cu NPs) surface-modified with cardanol poly(oxyethylene xanthate) (CPEOCS2K). By combining the two through in situ polymerization, a nanocomposite emulsion lubricant with a core-shell structure exhibits excellent stability, lubrication, and load-carrying capacity. Under test conditions of 294 N load, the 1.0 wt % Cu NPs/PBMS formulation achieved an optimal friction coefficient of 0.066, a wear scar diameter of only 474.9 μm, and a maximum nonseizure load of 1403 N. The excellent tribological properties of the Cu NPs/PBMS composite emulsion are attributed to the synergistic interaction between the two components, which form a dense lubricating film at the friction interface, effectively isolating direct steel/steel contact. The work provides a new strategy for designing and preparing composite emulsion lubricants and expands their potential applications in lubrication.