title: Microrheology close to an equilibrium phase transition.
abstract: We investigate the microstructural and microrheological response to a tracer particle of a two-dimensional colloidal suspension under thermodynamic conditions close to a liquid-gas phase boundary. On the liquid side of the binodal, increasing the velocity of the (repulsive) tracer leads to the development of a pronounced cavitation bubble, within which the concentration of colloidal particles is strongly depleted. The tendency of the liquid to cavitate is characterized by a dimensionless "colloidal cavitation" number. On the gas side of the binodal, a pulled (attractive) tracer leaves behind it an extended trail of colloidal liquid, arising from downstream advection of a wetting layer on its surface. For both situations the velocity dependent friction is calculated.
authors.affiliation: Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Reinhardt
authors.affiliation: Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Scacchi
authors.affiliation: Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland.
authors.forename: J M
authors.initials: JM
authors.lastname: Brader