Evaporating droplets on oil-wetted surfaces: Suppression of the coffee-stain effect.

ABSTRACT: The evaporation of suspension droplets is the underlying mechanism in many surface-coating and surface-patterning applications. However, the uniformity of the final deposit suffers from the coffee-stain effect caused by contact line pinning. Here, we show that control over particle deposition can be achieved through droplet evaporation on oil-wetted hydrophilic surfaces. We demonstrate by flow visualization, theory, and numerics that the final deposit of the particles is governed by the coupling of the flow field in the evaporating droplet, the movement of its contact line, and the wetting state of the thin film surrounding the droplet. We show that the dynamics of the contact line can be tuned through the addition of a surfactant, thereby controlling the surface energies, which then leads

SUBMITTER: Li Y 

PROVIDER: S-EPMC7382233 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature