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Liquid-liquid coffee-ring effect
- Poulichet, Vincent, Morel, Mathieu, Rudiuk, Sergii, Baigl, Damien
- Journal of colloid and interface science 2020 v.573 pp. 370-375
- evaporation, industry, solutes, solvents
- The so-called coffee-ring effect (CRE) is extraordinarily common, problematic in industry and attractively puzzling for researchers, with the accepted rule that it requires two key-ingredients: solvent evaporation and contact line pinning. Here, we demonstrate that the CRE also occurs when the solvent of a pinned sessile drop transfers into another liquid, without involving any evaporation. We show that it shares all characteristic features of the evaporative CRE: solvent transfer-driven transport of solutes to the contact line, ring-shaped deposit, closely-packed particle organization at the contact line, and size-dependent particle sorting. We thus suggest expanding the definition of the coffee-ring effect to any pinned drop having its solvent transferring to an outer medium where the drop compounds cannot be dissolved.