Inhomogeneous surface tension of chemically active fluid interfaces

Abstract

We study the dependence of the surface tension of a fluid interface on the density profile of a third suspended phase. By means of an approximated model for the binary mixture and of a perturbative approach we derive close formulas for the free energy of the system and for the surface tension of the interface. Our results show a remarkable non-monotonous dependence of the surface tension on the peak of the density of the suspended phase. Our results also predict the local value of the surface tension in the case in which the density of the suspended phase is not homogeneous along the interface.

Phoretic colloids close to and trapped at fluid interfaces

“…Crossing . A fluid‐fluid interface can be crossed by the reaction products of the catalysis [31] . This is crucial because it implies that the density profile of reaction products in one fluid phase can be controlled upon tuning its dynamics in the other one.…”

“…Responsive . Fluid‐fluid interfaces can be responsive to the imbalance in the chemical potential [31] and this can lead to the onset of Marangoni flows that, again, is absent in the case of solid‐fluid interfaces.…”

Phoretic colloids close to and trapped at fluid interfaces

“…While both fluid-fluid and solid-fluid interfaces affect the performance of phoretic particles by deforming the chemical potential profile, fluid-fluid interfaces are characterized by some peculiar features, absent in the case of solid-fluid interfaces: Crossing. A fluid-fluid interface can be crossed by the reaction products of the catalysis [31]. This is crucial because it implies that the density profile of reaction products in one fluid phase can be controlled upon tuning its dynamics in the other one.…”

“…In such a case, their collective behavior is affected by capillary interactions that are absent in the case of fluid-solid interfaces Responsive. Fluid-fluid interfaces can be responsive to the imbalance in the chemical potential [31] and this can lead to the onset of Marangoni flows that, again, is absent in the case of solid-fluid interfaces.…”