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キーワード:
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要旨:
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.
