Structure-property relationship and tunable lubrication mechanism of non-covalently modified graphene oxide by imidazolium ionic liquids under molecular structure scale

Designing novel additives to form multilayer integrated lubrication film provides an effective approach for developing composite nano-lubrication systems with superior comprehensive performance. Five halogen-free ionic liquids (ILs) with varying anionic structures were synthesized, providing a detailed investigation into the directional regulation of the properties of Graphene oxide (GO) by ILs with different molecular structures, as well as the structure-property relationships and tunable lubrication mechanisms between ILs and GO. The results indicated that, in ILs, the adsorption of polar sulfonic acid groups, and the presence of flexible alkyl chains, rigid aryl rings and active elements, contributes to the formation of a more stable polar adsorption and tribochemical reaction film during friction. Concurrently, the structural alterations of ILs effectively modulated the properties of GO, facilitating an in-situ synergistic lubrication effect between GO and ILs. From the perspective of ILs molecular structure design, the key anionic structures regulating the comprehensive performance of GO were investigated, and this work can provide experimental and theoretical guidance for the design and development of high-performance nano additives and solid-liquid composite lubrication systems.