  Hypothesis: Multi-component droplet evaporation has received significant
attention in recent years due to the broad range of applications such as
material science, environmental monitoring, and pharmaceuticals. The selective
evaporation induced by the different physicochemical properties of components
is expected to influence the concentration distributions and the separation of
mixtures, thereby leading to rich interfacial phenomena and phase interactions.
Experiments: A ternary mixture system containing hexadecane, ethanol, and
diethyl ether is investigated in this study. The diethyl ether exhibits both
surfactant-like and co-solvent properties. Systematic experiments were
performed using acoustic levitation technique to achieve a contact-less
evaporation condition. The evaporation dynamics and temperature information are
acquired in the experiments, using high-speed photography and infrared
thermography technologies. Findings: Three distinct stages, namely, "Ouzo
state", "Janus state", and "Encapsulating state", are identified for the
evaporating ternary droplet in acoustic levitation. A self-sustaining periodic
freezing & melting evaporation mode is reported. A theoretical model is
developed to characterize the multi-stage evaporating behaviors. We demonstrate
the capability to tune the evaporating behaviors by varying the initial droplet
composition. This work provides a deeper understanding of the interfacial
dynamics and phase transitions involved in multi-component droplets and
proposes novel strategies for the design and control of droplet-based systems
