Poly(ionic liquid)s with amino acids counterions as multifunctional water-based additives contributing to green lubrication

Three halogen-free poly(ionic liquid)s (PILs), composed of polycations (poly(PEGMA-co-METAC), PPM) and different amino acid anions as counterions, were synthesized. The physicochemical properties of three PILs were characterized to confirm their efficacy as viscosity-enhancing additives. The tribological properties of aqueous lubricants containing PILs were investigated by the SRV-IV test. The addition of three PILs to water resulted in remarkable improvements in kinematic viscosity, lubricity, and anti-wear properties. Among them, PPM-Try demonstrated the best tribological performance due to the formation of the more superior protective film on the friction interface through a tribochemical reaction. Furthermore, PPM-Try is non-toxic to environment and demonstrates favorable antibacterial properties, rendering it a promising eco-friendly aqueous lubricant additive for applications in the metalworking and food industry. [Display omitted] •Three halogen-free PILs with amino acids counterions were prepared and employed as water-based lubricant additives.•PILs can significantly enhance the viscosity, corrosion resistance, friction reduction and anti-wear properties of water.•Three types of tribofilms act synergistically to endow PILs with superior tribological properties.•PPM-Try demonstrates favorable antimicrobial activities and low biotoxicity towards earthworm.