Highly stable surface functionalized MoS2 nanoparticles as high temperature lubricant additives: Nanostructural insights from SANS

There is currently an urgent need for sustainable high temperature lubricant additives in critical industrial applications. Inorganic nanoparticles (NPs) have been intensively investigated as lubricant additives. However, it is extremely challenging to synthesize highly stable NP dispersions in non-polar media. We have prepared surface functionalized molybdenum disulfide (FMoS2) NPs with unprecedented long-term stability (over 1 month or longer) in a range of nonpolar solvents, using a simple and scalable method via ball milling, in a systematic effort to address the bottleneck of poor NP dispersibility in liquid media. This opens up a new pathway for preparation of surface modified NPs, facile and highly versatile – which can be used as friction-reducing and anti-wear (AW) additives in polar base oils and nonpolar hydrocarbon oils by varying the tail group chain polarity using different polymers. Moreover, tribological measurements indicates that the addition of FMoS2 NPs in PAO significantly reduced the friction of base oil and protected the surface from wear at elevated temperatures. Here, we propose first SANS characterization of dispersion of FMoS2 NPs in oil (n-dodecane), proving definitive nanostructural information on the size, shape, and structure of this highly innovative stable nanofluid. The results will underpin future rational design of surface functionalized NPs as a new class of high temperature (HT) lubricants.