Patterning of small particles by a surfactant-enhanced Marangoni-Bénard instability.
Evaporating drops provide a means of organizing particles suspended within them. Here, the manner in which surfactants alter these patterns is studied as a function of the surface state of an insoluble monolayer at the drop interface. The surface state is visualized throughout the drop evolution using fluorescence microscopy. A regime of surfactant coverage is identified that creates conditions that enhance the Marangoni-Bénard instability. This result was not anticipated in prior studies, in which surfactants are predicted to prevent this instability. These data demonstrate that, by tuning the liquid-gas boundary condition, the patterns formed from an evaporating drop can be controlled.
Nguyen
Van X
VX
Department of Chemical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Stebe
Kathleen J
KJ