Nano‑copper lubricant additive based on Triton modifier: Synergistic physical-chemical friction reduction mechanism and performance optimization

The development of eco-friendly water-based lubricants is significantly limited by their insufficient tribological performance. To address this challenge, we developed two novel Triton-based surface modifiers (Modifier-100 and Modifier-114) for synthesizing water-soluble copper nanoparticles (Cu NPs) through direct surface modification. Structural characterization demonstrated that Tx 100-Cu NPs exhibited superior dispersion stability with a uniform particle size distribution of 5 nm, while Tx 114-Cu NPs showed significant clustering with a broader size distribution. Tribological evaluations revealed remarkable improvements: at an optimal concentration of 0.5 %, Tx 100-Cu NPs reduced the friction coefficient to 0.08 (81.7 % reduction compared to pure water) and decreased wear volume by 71.67 %, while Tx 114-Cu NPs achieved a friction coefficient of 0.10 (80.8 % reduction) with 61.36 % wear volume decrease. The exceptional performance originates from a synergistic lubrication mechanism involving both physical protection through copper mesh film formation and micro-ball rolling effects, combined with chemical generation of anti-wear compounds via tribochemical reactions. This work demonstrates that strategically designed surface-modified Cu NPs can effectively enhance water-based lubricants through multi-mechanistic cooperation, providing a promising pathway toward sustainable lubrication solutions. • Designed Triton-modified Cu nanoparticles (5 nm) with excellent water dispersion. • Achieved 81.7 % lower friction (0.08) and 71.67 % less wear vs. water, with 6× higher load capacity. • Combined nanoparticle rolling and chemical films (FeS/Fe₂(SO₄)₃) for dual lubrication. • Maintained performance across industrial conditions (98–392 N loads, 600–1450 rpm speeds).