Deep eutectic solvent intercalation graphene oxide with strong interfacial adsorption capacity towards efficient lubrication

The high-performance lubrication effect of graphene materials is mainly due to the formation of friction film. However, the poor compatibility and interfacial adsorption of graphene oxide restrict the density of the friction film, thus losing the expected lubrication performance. Herein, the novel oil-based lubricant additives were configured by deep eutectic solvents (made of choline chloride and ethylene glycol) intercalation graphene oxide (DES-GOs). The strong hydrogen bonding between deep eutectic solvents (DESs) and graphene oxide nanosheets was detected. Precipitate experiment and UV–vis absorption spectra demonstrated high dispersion stability of DES-GOs1:3 in PEG 200 (no precipitate after 120 days). Significantly, DES-GOs1:3 with excellent electrical conductivity possessed the outstanding lubrication performance, whose average friction coefficient and wear volume decrease by 38.3% and 91.2%, compared with PEG 200, respectively. The proposed reasons to this enhanced performance were the synergistic effect of high dispersion stability, formation of the dense tribo-films and low inter-layers shear effect. Considering the diversity of DESs components and two-dimensional materials, the novel DESs functionalized two-dimensional materials possess great potential in industrial application as lubricant additives for different working conditions and base oils.