Liquid drops attract or repel by the inverted Cheerios effect

S. Karpitschka, A. Pandey, L.A. Lubbers, J.H. Weijs, L. Botto, S. Das, B. Andreotti, J.H. Snoeijer

    Research output: Contribution to journalArticleAcademicpeer-review

    67 Citations (Scopus)

    Abstract

    Solid particles floating at a liquid interface exhibit a long-ranged attraction mediated by surface tension. In the absence of bulk elasticity, this is the dominant lateral interaction of mechanical origin. Here, we show that an analogous long-range interaction occurs between adjacent droplets on solid substrates, which crucially relies on a combination of capillarity and bulk elasticity. We experimentally observe the interaction between droplets on soft gels and provide a theoretical framework that quantitatively predicts the interaction force between the droplets. Remarkably, we find that, although on thick substrates the interaction is purely attractive and leads to drop-drop coalescence, for relatively thin substrates a short-range repulsion occurs, which prevents the two drops from coming into direct contact. This versatile interaction is the liquid-on-solid analog of the "Cheerios effect." The effect will strongly influence the condensation and coarsening of drops on soft polymer films, and has potential implications for colloidal assembly and mechanobiology.

    Original languageEnglish
    Pages (from-to)7403-7407
    Number of pages5
    JournalProceedings of the National Academy of Sciences of the United States of America (PNAS)
    Volume113
    Issue number27
    DOIs
    Publication statusPublished - 5 Jul 2016

    Keywords

    • Droplets
    • Elastocapillarity
    • Mechanosensing
    • Soft matter
    • Wetting

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