Taming the diffusiophoretic convective instability in colloidal suspensions.

A suspension of Brownian colloidal particles stabilised against aggregation is expected to be stable against convection when its density decreases monotonically with height. Surprisingly, a recent experimental investigation has shown that when colloidal particles are dispersed uniformly in a solvent with a stabilising stratification of a molecular solute, the system develops a convective instability under generic conditions [Anzivino , , 2024, , 9030]. This instability arises because the solute concentration gradient induces an upward diffusiophoretic motion of the colloidal particles, triggering a diffusiophoretic convective instability (DCI).