Biodegradable glucosamine-amino acid-based ionic liquids as efficient water-based lubricant additives for green tribological chemistry

Abstract

Water-based lubricants demonstrate significant development potential in machining and automotive manufacturing industries owing to their environmental friendliness, safety profile, and ease of cleaning. In this study, two eco-friendly amino acid-based ionic liquids (AAILs), N-ethyl-D-glucamine-2-(N-methyldodecanamido) acetate acid (EDG-LS) and N-octyl-D-glucamine-2-(N-methyldodecanamido) acetate (ODG-LS), were synthesized using 2-(N-methyldodecanamido) acetic acid and glucosamine as raw materials. When AAILs were employed as water-based lubrication additives, the physicochemical characteristics, tribological performances, and lubrication mechanisms of the lubricants were systematically evaluated. The results of the cast iron tests demonstrate that adding just 1 wt% of AAIL additives can significantly reduce the corrosion of water. Moreover, EDG-LS exhibits superior friction reduction (69.9% decrease) and anti-wear properties (91.4% reduction) compared to water. The combined influence of physically adsorbed films and tribochemical reaction layers endows AAILs with outstanding tribological performance. Additionally, two kinds of AAILs exhibit favorable biodegradability, with a biodegradation rate approaching 60%. This research provides theoretical insights for creating eco-friendly, biodegradable, and multifunctional water-based lubricant additives.