Molecular Dynamics Study of Droplet Impinging/Freezing on Cold Surface

Rapid freezing is utilized for cell preservation without the application of cryoprotectants to rapidly freeze water-containing specimens such as living organisms, foods, and paints.Prior studies have predominantly focused on the freezing behavior of micrometer-to-millimeter-sized droplets on cold surfaces, examining variables such as droplet shape and freezing time.However, the freezing dynamics of nanometer-sized droplets on cold surfaces remain unexplored.In this study, we employed molecular dynamics (MD) simulations to investigate the freezing behavior of nanometer-sized droplets impacting a cold surface.We did not observe a corner forming at the top of the nanometersized droplets because the freezing process was too rapid for internal flow to develop.Our findings indicate that the droplet's temperature rapidly increases due to the heat of adsorption upon contact with the surface and the conversion of kinetic energy.Furthermore, we found that the contact angle post-freezing is influenced by multiple factors, including wettability, temperature of cold surface, impact speed, and droplet size.