Polymerization-Induced Self-Assembled Micelles in Oil as Lubricant Additives with Enhanced Tribological Properties

Lubricant additives (LAs) play a crucial role in enhancing the lubrication performance and durability of oils. However, inorganic nanoparticle (INP) LAs often encounter challenges related to poor dispersion stability. Here, polymer micelles were investigated as potential LAs to evaluate their effect on the lubricating properties of base oils and to explore their friction reduction mechanism. Through the polymerization-induced self-assembly (PISA) approach, spherical micelles of the block copolymer poly(lauryl methacrylate)–poly(benzyl methacrylate) (PLMAx–PBzMAy) were synthesized in oil. These micelles, prepared in situ, exhibited exceptional dispersion stability surpassing that of inorganic nanoparticles (SiO2) for over 300 days. Tribological testing revealed that the self-assembled micelles could disentangle to form a robust layer of a polymeric tribofilm, effectively preventing wear on the contacting surfaces during friction. Consequently, the load-bearing capacity was significantly enhanced to 1000 N while maintaining a stable low coefficient of friction (COF) and low wear rate. This work presents a design protocol for LAs distinguished by their superb dispersion stability, antifriction, and antiwear characteristics.