Zwitterionic microgel-functionalized gallium-based liquid-metal nanodroplets as aqueous lubricant additives

Herein, a bioinspired molecule-dopamine n-butenylamide-was self-assembled on Gallium-based liquid metal (GLM) nanodroplets to introduce vinyl group, and the zwitterionic poly (2-methylacryloxyethyl phosphocholine) (PMPC) was grafted onto GLM nanodroplets via surface-initiated free radical polymerization to obtain hybrid PMPC-GLM microgel. The as-prepared PMPC-GLM microgel has good dispersion stability in aqueous solution (chemical stability > 2 months), and shows excellent antibacterial properties due to the hydration of PMPC and antibacterial effect of Ga3+. Moreover, the hydration layer endows PMPC-GLM microgel with satisfactory tribological properties as an aqueous lubricant additive, with the COF and wear rate reduced by 65% and 62%. In addition to hydration lubrication, the improved tribological performance is attributed to the formation of pro-tective film on the worn surface.