Dynamics of Thin Lubricant Films upon Liquid Contact on Slippery Surfaces

Abstract: In recent years, slippery surfaces have attracted significant interest due to their excellent liquid-repellent properties and their potential in diverse commercial applications. Such surfaces are prepared by coating functionalized solid substrates with a thin lubricant film that prevents direct contact between a liquid and the substrate. The morphology of thin films upon liquid contact plays a central role in governing various phenomena, including the coalescence and mobility of liquid droplets, heat transfer efficiency, and the extent of lubricant depletion. However, a detailed understanding of film dynamics upon droplet contact remains limited, both from theoretical and experimental perspectives. Here, by employing principles of fluid dynamics, optics, and surface wetting, we present a comprehensive study that examines both the spatial and temporal variations of lubricant films upon contact with sessile liquid droplets and liquid bridges. Our findings reveal that the film dynamics can be categorized into three distinct stages, each significantly influenced by key system parameters: initial film thickness, three-phase contact line width, and Laplace pressure of liquids. Furthermore, we demonstrate that by optimizing these parameters, it is possible to reverse the lubricant flow in the final stage, thereby causing the liquid to partially lift off from the slippery surface.