Stable and Unstable Lubricant Impregnated Surfaces (LIS) under water and oil environment

In nature, liquid wetting and dewetting on solids occurs naturally and spontaneously. Some natural occurrences, such as a raindrop falling and spreading on leaves, have the fundamental attribute of a liquid drop spreading on a surface. Most of the natural spontaneous imbibition processes involve the interaction of capillary and viscous forces. For quite a while, researchers have been investigating how liquid and solid interact. Additionally, it involves more complexities when liquid-liquid and/or liquid-solid interactions are in place such as in case of spreading of a liquid on solid inside another liquid environment instead of being in an air environment. The primary source of fluid flow in a porous medium is typically thought to be the capillary pressure that resulted from the interfacial tension and sub mm scale geometry or roughness features of the solid surface. How surface roughness, interfacial energies and fluid viscosities affect wetting phenomena inside a liquid environment is still not clearly understood. The Classical Lucas Washburn (CLW) equation relates the capillary imbibition force through a cylinder with the viscous resistance force. Flow of one liquid on the textured surface in the presence of another liquid pre-existing inside the texture became more complex and difficult to analyze. One such example is of unstable Liquid Impregnated Surface (LIS) where a lubricant oil present in the texture is replaced by an environmental fluid. In the proposed Modified Lucas Washburn (MLW), the contact angle of the spreading phase in the lubricant oil phase and the sum of (spreading and lubricant fluid) viscosity was considered for the theoretical calculation. The results of this study provide valuable insights into the fundamental mechanisms governing oil stability on LIS. These findings include guidelines for enhancing LIS design parameters and operating conditions to obtain enhanced performance in real-world applications and prolonged durability.