Evaporation and dissolution of droplets in ternary systems

Abstract

The evaporation and dissolution of droplets in multi-component systems are omnipresent in nature, science, and many advanced technologies. However, these droplets have much less been studied than droplets consisting of a pure liquid only. The two-way interactions between the fluid properties and hydrodynamics make the dynamical behavior of the droplet complicated. In this thesis, we give our contributions to this field by studying the evaporation and dissolution of Ouzo droplets. Ouzo is an anise-flavored aperitif, primarily consisting of water, ethanol and a small amount of anise oil. The Ouzo droplet may be seen as a model system for any ternary mixture of liquids with different volatilities and mutual solubilities. In Part I, we explored the evaporating and dissolving processes of “ouzo” (water, ethanol, and anise oil) droplets on surfaces. Through a series of studies, we revealed microdroplet nucleation processes triggered by the evaporation or dissolution of the droplets in ternary systems and consequently induced dynamical behaviors of the droplets. In Part II, we performed exploratory research on the application of the evaporating multicomponent droplets. Inspired by the interesting phenomenon observed in Part I, we proposed a method for evaporation-driven particles assembly. Through this method, the evaporating colloid ouzo droplets acquire a “self-lubrication” ability, which improves the supraparticle fabrication technique. In the last Part III, our attention focused on the nucleated nanodroplets on the surface induced by the “ouzo effect.” We used the solvent exchange method to form the surface nanodroplets in a narrow channel with controlled flow conditions. A comprehensive three-dimensional (3D) spherical cap fitting procedure was developed for the accurate extraction of the morphologic characteristics of complete or truncated spherical caps from atomic force microscopy (AFM) images.