Material design for adaptive lubrication: Synergistic construction of dynamic gradient tribofilm by regulating functionalized graphene oxide with oleophilic poly(ionic liquid)

The rapid advancement of miniaturized and lightweight precision instruments is placing increasingly stringent demands on the lubricating protective films at friction interfaces. In this study, a nanocomposite lubricating additive consisting of poly(ionic liquid)-P[V 6 mim]SDBS (PIL) modified graphene oxide (PGO) was synthesized. This establishes a PGO-PIL/PAO 10 composite lubrication system exhibiting tunable viscosity-temperature properties, excellent thermal stability and outstanding friction reducing and anti-wear performance. With the optimal lubricant system (2.0 wt% PIL+1.0 wt% PGO), a low coefficient of friction (CoF) as low as 0.06 and reduces wear by 92.5 % compared to PAO 10 base oil. Crucially, a multifunctional integrated tribofilm with a multilayer structure was successfully formed at the friction interface, synergistically achieving strong adsorption, superior anti wear properties and adaptive lubrication. In-depth mechanism analysis indicates that the excellent tribological performance stems from the dynamic synergistic interaction among a carbonaceous reorganized film formed by PIL and PGO, a tribochemical reaction layer containing active elements, a physicochemical adsorption layer anchored by polymer chains, and a deep metal oxide layer, providing new insights into the adaptive behavior of the PGO-PIL system at metal interfaces. This work establishes the exceptional adaptive lubrication and self-healing capabilities of the PGO-PIL nanocomposite, while further deciphering the synergistic mechanism that underpins its enhanced tribological behavior. The performance regulation achieved through noncovalent modification of GO by the flexible adsorption structure of PIL is crucial for developing multifunctional, high-performance nanolubricants with excellent structure-property relationships.