Electrical stimulation enables dynamic regulation of the tribological behaviors of polyelectrolyte-modified carbon dots

Abstract

Dynamic and active control of the tribological behaviors of lubricant additives under electrical stimulation is important for the development of electromechanical devices. Carbon dots (CDs) show great prospects in electrical contact lubrication owing to their easily acquired oil dispersibility, ionic conductivity, and high lubricity. Herein, the polyelectrolyte-modified CDs (PCDs) were synthesized from the chitosan-derived polyamine-terminated CDs. The PCDs can be stabilized in polyethylene glycol (PEG200) synthetic oil for more than one year without any precipitates and fluorescence decay. Compared with neat PEG200, the formulated PCDs (0.25 wt%)/PEG200 lubricant achieved 63.6% and 39.1% reductions in wear and friction, respectively. In addition, the durability of PEG200 also can be enhanced by PCDs. Crucially, the friction regulation of PCDs under external electric fields (as low as ±1.0 V) was easily realized for the first time, which effectively helps to reveal the indispensable role of polyelectrolyte shells in improving the tribological performances of PCDs. Experiments and characterizations demonstrated that the superior tribological peculiarities of PCDs benefited from the collaborations of their polyelectrolyte shells and carbon cores. The findings provide a universal protocol and material support for expediting the potential-controlled lubrication progress of nano-additives.