Adhesion energy per unit area various liquid droplets on PMMA, Parylene C and PPFC coated flat solid surfaces

Abstract

The adhesion force of a liquid droplet on a solid surface is a key factor influencing mobility of liquid droplets on the solid surface. Most of previous adhesion force models consider the length of the periphery of the wet area even though all parts in the wet area contribute to the adhesion of a liquid droplet. Recently, the authors proposed a new method to determine the adhesion energy of a droplet on a flat solid surface and this concept was verified using various liquid droplets on a hydrophobic solid surface. In this study, experiments are performed to verify that the new concept also can be applied to hydrophilic surfaces. Experimental measurements and analysis of these data demonstrates that the new definition of adhesion energy per unit area is appropriate for describing the movement of a liquid on hydrophilic solid surfaces as well as hydrophobic solid surfaces.