The multi-hydroxyl hydrogen bond network structure of cation-responsive protonic ionic liquid water-based lubrication and their system interaction

Functional additives are crucial for achieving high performance at low concentrations to the polyethylene glycol water-based lubricants (PEG-H 2 O), further affecting their broad application prospects for industrial lubrication. Herein, the novel protic ionic liquids (ILs) were synthesized and introduced as functional additives to construct the high-performance water-based lubrication system. The improved corrosion resistance and adsorption performance is ascribed to the strong adsorption. And the friction coefficient and wear volume decreased by 60 % and 55 %, respectively. More importantly, superior lubrication stability can be obtained at high-load (800 N) and high-frequency (100 Hz) condition. This enhanced performance mainly depends on self-assembly behavior of IL molecules at the sliding interface, as well as synergistic effect of adsorption layer, H-bond network and tribo-chemical reaction. Besides, the dihydroxy structure in the cation is more conducive to the optimal molecular self-assembly structure. This work enriches design strategy of multifunctional water-based lubricants and sustainable lubrication technology.