Confinement suppresses instabilities in particle-laden droplets.

Area of Science:

• Fluid dynamics
• Materials science
• Colloid science

Background:

• Evaporating droplets with suspended particles exhibit complex behaviors, including mechanical instabilities like buckling and rupture.
• The morpho-dynamics of these droplets are influenced by particle concentration and droplet properties.

Purpose of the Study:

• To investigate the effects of confinement on the morpho-dynamics of evaporating colloidal droplets.
• To understand the mechanisms behind rupture suppression in confined evaporating droplets.
• To develop a regime map for buckling-non buckling pathways.

Main Methods:

• Experimental observation of evaporating droplets in confined environments.
• Analysis of droplet morpho-dynamics across macro to nano scales.
• Characterization of evaporating flux and internal flow patterns.

Main Results:

• Confinement non-intuitively suppresses droplet rupture beyond a critical threshold.
• Confinement significantly alters evaporating flux and internal flow dynamics.
• Distinct spatio-temporal particle transport leads to unique morphological transitions.
• A regime map was developed to quantify buckling and non-buckling pathways.

Conclusions:

• Confinement offers a novel method to control the mechanical instabilities and morphological outcomes of evaporating colloidal droplets.
• Tuning confinement, particle concentration, and droplet volume can achieve desired colloidal droplet features.
• These findings have implications for materials science and nanotechnology applications.