Tuning Contact Line Dynamics and Deposition Patterns in Volatile Liquid Mixtures

Abstract

The spreading of a pure, volatile liquid on a wettable substrate has been studied in extensive detail. Here we show that the addition of a miscible, non-volatile liquid can strongly alter the contact line dynamics and the final liquid deposition pattern. We observe two distinct regimes of behavior depending on the relative strength of solutal Marangoni forces and surface wetting. Fingerlike instabilities precede the deposition of a sub-micron thick film for large Marangoni forces and small solute contact angles, whereas isolated, pearl-like drops emerge and are deposited in quasicrystalline patterns for small Marangoni forces and large solute contact angles. This behavior can be tuned by directly varying the contact angle of the solute liquid on the solid substrate.

Spreading and retraction dynamics of sessile evaporating droplets comprising volatile binary mixtures

“…The fingering instability at the contact line resembles the ‘octopi’ instability observed by Mouat et al. (2020) and Gotkis et al. (2006) and is similar to the droplet ejection phenomena seen by Keiser et al.…”

“…The fingering instability at the contact line resembles the 'octopi' instability observed by Mouat et al (2020) and Gotkis et al (2006) and is similar to the droplet ejection phenomena seen by Keiser et al (2017) in ethanol-water droplets and Mouat et al (2020) in isopropanol-water droplets. Since the emergence of both instabilities only occurs at high initial ethanol concentrations, the clear indication is that they arise due to solutal Marangoni stresses.…”

“…(2017) in ethanol–water droplets and Mouat et al. (2020) in isopropanol–water droplets. Since the emergence of both instabilities only occurs at high initial ethanol concentrations, the clear indication is that they arise due to solutal Marangoni stresses.…”

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

“…Within the studies that aim for control over particle deposition by droplet evaporation, the approaches mainly focus on internal flow manipulation (8)(9)(10)(11)(12) and particle-solid interactions (13,14). In particular, Marangoni effects in evaporative multicomponent systems, either solutal (4,(15)(16)(17)(18)(19) or thermal (20), have been suggested as an effective way to suppress outward capillary flow by continuously mixing the suspended particles during the evaporation process. However, recent experimental observations on the evaporation of mul-ticomponent drops show complex physicochemical dynamics that can be triggered by selective evaporation such as phase separation (21)(22)(23) and crystallization (24).…”

Evaporation of Binary-Mixture Liquid Droplets: The Formation of Picoliter Pancakelike Shapes

“…A more extensive study of the parameter space spanned by different binary liquids will be presented in the future. It would be interesting to further explore the evaporation dynamics in the presence of surface roughness, different surface wetting conditions, spatiotemporal variations in the rheological properties of the mixtures, and phase separation [2,12,[47][48][49][50][51][52][53][54][55]. We anticipate our observations will have implications for many technological applications involving multicomponent drops [16,35,[56][57][58], where minute variation in surface tension due to nonuniform compositions within the drops can lead to strong flows and shape deformations.…”