Preparation of nanoscale liquid metal droplet wrapped with chitosan and its tribological properties as water-based lubricant additive

Gallium based liquid metals are emerging as promising lubricant candidates due to their high thermal stability and conductivity. However, the oxidization and instability of liquid metal limit their practical application in lubricant field. In this work, to overcome such problems, the nanoscale liquid metal droplet wrapped by chitosan (NLMWC) was fabricated through the ball milling method, which could be utilized as water-based lubricant additive. The microstructures of NLMWC as well as chemical stability and dispersion stability of NLMWC in water were observed. Moreover, our frictional tests demonstrate that when using NLMWC as additive in water, it holds good tribological performance including reduction of the friction coefficient and wear rate by 40% and 69%, in contrast to the pure water.