Tribological Properties of Polypropylene Adipate Base Oil Containing <i>In Situ</i> Catalytically Dispersed Spherical Nano-MoS<sub>2</sub>/Sericite

Polyester base oil has good lubricating properties and biodegradability, which meets the requirements of green and sustainable development. In this work, polypropylene adipate (PPA) was synthesized with spherical nano-MoS2/sericite (SMS) as catalyst. SMS did not need to be separated from PPA after the reaction and could be retained in PPA as a lubricant additive. The SMS precipitated slowly in the SMS/PPA suspension during standing storage, and after 7 days, there was still 1236 mg/L SMS in the PPA. Compared with PPA synthesized without SMS, the friction coefficient of the SMS/PPA suspension after standing for 7 days was reduced by 13.9%. Moreover, the suspension also decreased the wear volumes of the steel ball and the steel disc by 59% and 94%, respectively. The characterization results showed that SMS participated in the formation of tribofilm, and decomposed into silicon and oxygen-rich compounds filled in the peeling caves. This study provides an alternative path for the synthesis of polyester base oil, and also expands the potential application range of MoS2 lubricant additives.