Molecular Dynamics Study of the Temperature-Dependent Coalescence of Liquid Nanodrops: Implications for Microfluidics

Drop coalescence is central to diverse processes involving microfluidics in industrial, engineering, and scientific realms and has attracted much attention in recent years. Here, the effect of temperature on the coalescence of liquid nanodrops is investigated by using molecular dynamics simulations. Our data give visible evidence that the increase of temperature positively promotes the coalescence process featured by the enhanced mixing degree, resulting from the larger diffusion of atoms. More importantly, the temperature difference can affect the coalescence way, and therefore three metastable models of the coalesced nanodrop are found during coalescence, which are "uniform" type, "segregation" type, "wrapped" type. Interestingly, for the identical nanodrop, its diffusion can be enhanced when coalescing with a high-temperature nanodrop but restricted with a low-temperature nanodrop, which indicates the possibility of tuning coalescence by a temperature-controlled method. Besides, other temperature systems are also considered for further studying the effect of temperature, such as the same temperature-difference system. This work would provide a comprehensive molecular-level view of the effect of the temperature on the coalescence of liquid nanodrops and open up new ways to control microfluidics for some applications.