Regulation Mechanism of Trivalent Cations on Friction Coefficient of a Poly(Vinylphosphonic Acid) (PVPA) Superlubricity System

The application range of superlubricity systems can be extended effectively by realizing an adjustable friction coefficient. In this study, a stable poly(vinylphosphonic acid) (PVPA) system was developed using sodium chloride (NaCl) solution as the lubricant. A sudden increase in coefficient occurred when trivalent salt introduced to base lubricant during process. changes surface microstructure and interfacial molecular behavior induced cations were studied scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) dynamics simulation. regulation mechanism with respect PVPA explored. Although La3+ Fe3+ solutions exist two forms (La3+ Fe(OH)3), both destroy coating structure through bridging effect, resulting ability various attract surrounding water molecules is important reason for varying degree change addition, dependent on concentration cations. There extreme at which maximum obtained. This study provides insights into realization oil-based interface regulation.