Disjoining pressure analysis of the lubricant nanofilm stability of liquid-infused surface upon lubricant depletion

Abstract

HypothesisThe structure of the slippery layer and the evolution of functional properties of a lubricant infused substrate (LIS) is determined by the isotherm of disjoining pressure in the lubricant film. MethodsThe macroscopic theory of van der Waals forces was applied to the layered system used to model the structure and properties of LIS. For a lubricant layer sandwiched between the flat substrate and air or water, the isotherms of disjoining pressure were calculated and their analysis was used to conclude about stability of LIS. FindingsThe results obtained for silicone oil and perfluorodecalin on smooth and porous hydrophilic and hydrophobic solids allow selecting the LIS components corresponding to stability of lubricant films in air and water. It was found that for hydrophilic substrates in conditions of lubricant depletion, silicone oil and perfluorodecalin show lubricant film stability in both air and water. On flat or post microtexture hydrophobic substrate with flat tops, the perfluorodecalin lubricating layer is typically stable in air and unstable in water. In contrast, silicone oil lubricating layer demonstrates the stability in a wide range of lubricant film thicknesses for the hydrophobic substrate with flat-top textures in water, however, it can be unstable in air.