Achieving Greener, Super-Robust Performance Water-Based Lubrication: Obtained by a Multifunctional Ionic Liquid Aqueous System and Formation of Unique Interfacial Interactions

Abstract

Owing to the green, high-performance, and application-specific work conditions, water-based lubricating systems show unlimited potential for chemical engineering development. The interfacial behavior of functional additives in aqueous systems is complex and variable due to polarity and interfacial activity, thus showing important research significance. Herein, five novel ionic liquids were synthesized; their unique interfacial behavior in the polar water system contributes a lot to the advanced corrosion resistance and the improved extreme pressure-bearing capacity. The polar groups in the molecular structure of ionic liquids can adsorb preferentially in competition with water molecules, resulting in the formation of an adsorption layer with a high elastic modulus on the metal surface. Benefiting from the tribochemical reaction and the strong polar adsorption effect, the tribofilm at the sliding asperity exhibited effective antiscuffing and antiwear performance. Moreover, their characteristic cationic groups enrich the driving force of the molecular self-assembly process and enhance the ability to form ordered molecular aggregates, whose behavior in an aqueous system facilitates super-robust lubricity. This work can promote the in-depth understanding, future design, and optimization of the aqueous lubricating system, providing content enrichment and expansion for the lubrication technology for harsh service conditions.