Synthesizing Benzotriazole Group-Terminated Carbon Dots as Multifunctional Additives of Poly(ethylene glycol)

Long running-in period and corrosion problems have greatly hindered the practical applications of poly(ethylene glycol) (PEG) lubricants. In this work, benzotriazole group-terminated carbon dots (BT-CDs) were specifically synthesized through a facile solvothermal method. The benzotriazole groups on BT-CD surfaces not only imparted them excellent dispersibility in the PEG base oil but also brought in outstanding anticorrosion ability for BT-CDs. With the aid of the coordination effects between benzotriazole groups and metal atoms, the BT-CDs could quickly and solidly adsorb onto the steel surface to form a dense adsorption layer, which resulted in an amazing phenomenon, i.e., the disappearance of the running-in period for the friction test. Adding 5.0 wt % BT-CDs reduced the friction and wear of PEG200 by 49.16 and 49.52%, respectively. When the duration was prolonged from 20 to 120 min, these values were further enlarged to 53.77 and 60.71%. The worn surface characterization demonstrated that the BT-CDs induced the generation of robust lubricating films on the frictional interfaces, accounting for their distinguished tribological performance. Considering the superior anticorrosion ability and the potential possibility of avoiding the running-in period, the BT-CDs are expected to be developed as particularly promising additives toward PEG.