Mobility of A Water Droplet on Liquid Phase of N-Octadecane Coated Hydrophobic Surface

Abstract

A water droplet behavior on the liquid n-octadecane film is investigated. The coating of hydrophobic surface by N-octadecane film provides exchange of wetting state on the surface. The polycarbonate surface is crystallized and the functionalized silica particles are placed on the resulting surface prior to thin film coating of n-octadecane. A high-speed camera is used to monitor dynamic characteristics of the droplet on the inclined film. The findings reveal that deposition of thin n-octadecane film on hydrophobic surface results in reversibly exchange of the wetting state at the surface, which remains hydrophobic when n-octadecane film is in solid phase while it becomes hydrophilic when n-octadecane film liquefies. Droplet transition velocity predicted agrees well with the experimental data. Sliding mode of the water droplet governs droplet transition on the liquid surface. Droplet pinning force, due to interfacial tension, dominates over the other retention forces including drag and shear.

Janus Nanoparticle and Surfactant Effects on Oil Drop Migration in Water under Shear

“…The motion of liquid droplets is important to a broad range of process industries − and especially the petrochemical sector, where oil and water are often produced and transported together. , Several techniques can be exploited to make droplets move, such as electrostatic actuation, , surface energy gradient, , or external forcing by shear flow, − and several studies regarding the transportation of droplets have been performed either experimentally , or computationally. , Notably, most previous studies focused on the motion of droplets or bubbles in a cylindrical capillary. − For noncylindrical geometries, Horwitz et al studied the effect of the dimensionless parameters (Reynolds number and capillary number) and of the viscosity ratio between the droplet and the carrier fluid on droplet deformation in a square duct . More recently, Luo et al used a three-dimensional front-tracking finite-difference method to study the effects of the surfactant, including the reduced surface tension and the Marangoni stress, on the motion of a droplet in a square microchannel.…”

“…The motion of liquid droplets is important to a broad range of process industries 1−3 and especially the petrochemical sector, where oil and water are often produced and transported together. 4,5 Several techniques can be exploited to make droplets move, such as electrostatic actuation, 6,7 surface energy gradient, 8,9 or external forcing by shear flow, 10−13 and several studies regarding the transportation of droplets have been performed either experimentally 10,11 or computationally. 13,14 Notably, most previous studies focused on the motion of droplets or bubbles in a cylindrical capillary.…”