Abstract
Ionic liquids (ILs) have been recognized as an emerging type of solvent that feature exceptional stability, versatile solvent-solute interactions and exhibit a remarkable friction-reducing capability. On the other hand, surface-grafted solvated polymer films are known to mitigate friction and wear, while their performance is directly influenced by the associated solvent. To explore the potential synergy between the two systems, we compare the lubrication mechanisms of a neat IL and the corresponding polymer-IL system, as well as the influence of ambient humidity. Speed- and load-dependent lateral force microscopy was conducted in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Friction was modeled by considering adhesive and viscous contributions, which enables us to unveil the influence of molecular relaxation times and lengths. Previous research has demonstrated the role of water in determining the interfacial structure of the selected systems. The present study also endeavors to elucidate, from a molecular perspective, the impact of water in the lubrication behavior of the selected systems.