ESPCI web site
Phase separation of a confined binary mixture in a temperature gradient : impact of wetting and Marangoni strains
Our research focus on the phase separation of a thermoresponsive binary
mixture, which demix upon heating (LCST system). Critical phenomena
related to this phase transition have been studied in detail, and here
we do not look after fine and critical behaviors. Our interest lies in
the separation dynamics of this mixture at the centimeter scale, as many
applications have been proposed with those thermoresponsive systems.
Our ewperiments are performed in micrometric cavities such that
capillary effects play a significant role in the separation. With the
help of a temperature gradient, demixing is strongly enhanced thanks to
thermocapillary and wetting effects. Depending on the composition of the
mixture (ratio of both liquids) and on which phase is wetting the walls,
we identify three patterns of separation : two of them lead to the
accumulation of the wetting phase at the hot side of the cavity, the
third one presents less interest. I will present these 3 patterns and
explain the mechanisms responsible for the selective accumulation. We
conclude that those behaviors should be universal to all binary
mixtures.