Contact Angle of an Evaporating Droplet of Binary Solution on a Super Wetting Surface

Abstract

We study the dynamics of contact angle of a droplet of binary solution evaporating on a super wetting surface. Recent experiments show that although equilibrium contact angle of such droplet is zero, the contract angle can show complex time dependence before reaching the equilibrium value. We analyse such phenomena by extending our previous theory for the dynamics of an evaporating single component droplet to double component droplet. We show that the time dependence of the contact angle can be quite complex. Typically, it first decreases slightly, and then increases and finally decreases again. Under certain conditions, we find that the contact angle remains constant over a certain period of time during evaporation. We study how the plateau or peak contact angle depends on the initial composition and the humidity. The theory explains experimental results reported previously.

arXiv comment19 pages, 5 figures, to be published in Soft Matter

References in corpus (5)

• Evaporating pure, binary and ternary droplets: thermal effects and axial symmetry breaking
• Ring to Mountain Transition in Deposition Pattern of Drying
• Evaporation-triggered segregation of sessile binary droplets
• Vapor-Induced Motion of Liquid Droplets on an Inert Substrate
• Multi-Ring Deposition Pattern of Drying Droplets

Cited by in corpus (2)

• How liquid-liquid phase separation induces active spreading
• Physiochemical hydrodynamics of the phase segregation in an evaporating binary microdroplet