Treelike polymeric phosphate esters grafted onto graphene oxide and its tribological properties in polyalkylene glycol for steel/steel contact at elevated temperature

Abstract

We report the first synthesis of a high-performance lubricant additive by grafting treelike polymeric phosphate esters (PPEs) onto graphene oxide (GO) nanosheets. Characterization of the PPEs modified GO (GO–PPEs) was performed by spectral (FT-IR, Raman, SEM, TEM, XPS), and thermogravimetric analysis (TGA). Performance evaluations of GO–PPEs as a high-temperature friction-reduction and anti-wear additive in polyalkylene glycols (PAG) were conducted by an Optimol SRV-IV oscillating reciprocating friction and wear tester. The results indicated that GO–PPEs possessed excellent tribological properties in PAG compared with pure GO and PPEs under the same conditions, which may be attributed to the good dispersion of GO–PPEs in PAG, and the excellent tribological properties of phosphate at elevated temperature. In addition, the wear mechanism was tentatively discussed according to the surface composition.