Fluid-like carbon dots-based ionic fluid towards high efficient lubricant nanoadditive of polyethylene glycol

Solid polyelectrolyte grafted carbon dots as a precursor were synthesized using citric acid and poly(sodium 4-styrene sulfonate) via pyrolysis route, which were then capped by block copolymer to produce solvent-free carbon dots-based ionic fluid (CDs-PSS-M2070). The tribological performance of CDs-PSS-M2070 under different concentrations and loads was evaluated in polyethylene glycol (PEG). The results verified that CDs-PSS-M2070 efficiently improved the friction-reducing and wear-resistance performance as well as the load-bearing capacity of PEG in a broad load. The addition of 1.0% CDs-PSS-M2070 reduced wear volume of 82.8% and friction coefficient of 73.5% under the load of 392 N. Owing to the excellent dispersion of carbon dots ionic fluid in PEG, CDs-PSS-M2070 could continue to transfer to the frictional interface and form a continuous carbon-rich oil-film, thereby enhancing friction-reducing and wear-resistance abilities efficiently. • Solvent-free carbon dots-based nanofluid, namely CDs-PSS-M2070, was proposed and synthesized. • Carbon dots nanofluid exhibited excellent dispersion stability in polar PEG. • 1.0% CDs-PSS-M2070 in PEG could reduce wear volume of 82.8% and friction coefficient of 73.5% under boundary lubrication. • The excellent dispersion and charged nature of carbon dots-based nanofluid helped enhance the tribological abilities.