Synergistic lubrication mechanism and dispersion behavior of dodecanethiol-modified graphene oxide nanolubricant

Abstract

To enhance both the load-bearing capacity and dispersion stability of graphene oxide (GO), this study proposes a novel nanolubricant design approach. A dual-function additive acting as both a surface modifier and an extreme pressure agent, dodecanethiol (DDT), was introduced into the GO nanolubricant. As a pioneering dispersion method, sodium dodecyl sulfate-oleic acid (SDS-OA) gelators were incorporated to drag DDT-modified GO (GO/DDT) through the Van der Waals force between alkyl chains, which enables GO/DDT nanolubricant maintain stable dispersion in white oil (WO) for over one year. Additionally, the well-dispersed GO/DDT nanolubricant exhibit superior anti-friction, anti-wear and extreme pressure property under minimum quantity lubrication conditions. Compared with WO, the coefficient of friction (COF) and wear scar diameter (WSD) under 0.06 wt% GO/DDT nanolubricant lubrication were reduced by 31.9% and 28.8%. These are attributed to the fact that the modifier DDT not only participates in the molecular attraction with the gelators to inhibit the sedimentation of GO nanosheets, but also synergizes with GO to form both physical protective films and chemical reaction films on the friction surface.