MoS₂ micro/nano structure: preparation and tribological properties as additives in biodegradable polymer and ester oil

Abstract The needs of modern industry for high-performance lubricants remain difficult to meet. Therefore, finding ways to improve their lubrication performance is crucial. A novel composite consisting of two different structures of the same compound was synthesized for improving tribological properties. Flake-like micron MoS 2 (M-MoS 2 ) with a size of approximately 10 μm was activated via oxidation, ultrasonication, and grinding. The desired MoS 2 micro/nano structure (MN-MoS 2 ) was prepared through the chemical deposition of hollow spherical nano-MoS 2 with a diameter of approximately 75 nm on the activated M-MoS 2 . MN-MoS 2 combined the advantages of the micron and nano structures and possessed excellent tribological properties in both a solid lubricating system of polylactic acid (PLA) and a liquid lubricating system of diisooctyl sebacate (DIOS). In PLA, the addition of 0.1% MN-MoS 2 reduced the wear rate by 59.7%, but slightly increased the coefficient of friction (COF) by 3.1%. When the addition amount was increased to 0.5% in PLA, MN-MoS 2 can decrease the COF by 11.75%. In DIOS, the addition of 0.5% MN-MoS 2 reduced the wear rate by 58.9% and the COF by 37.2%. The lubrication mechanisms of the MN-MoS 2 -modified PLA were the formation of a MoS 2 /PLA transfer layer on the counterpart surface and the improvement in the thermal stability and hardness of PLA. However, the lubrication mechanism of the MN-MoS 2 -modified DIOS was mainly the formation of a stable friction film containing MoS 2 on the friction surface. These findings provide a way to improve the performance of lubricant additives and demonstrate potential application value.