Effective interaction between a colloid and a soft interface near criticality

Abstract

Within mean-field theory we determine the universal scaling function for the effective force acting on a single colloid located near the interface between two coexisting liquid phases of a binary liquid mixture close to its critical consolute point. This is the first study of critical Casimir forces emerging from the confinement of a fluctuating medium by at least one soft interface, instead by rigid walls only as studied previously. For this specific system, our semi-analytical calculation illustrates that knowledge of the colloid-induced, deformed shape of the interface allows one to accurately describe the effective interaction potential between the colloid and the interface. Moreover, our analysis demonstrates that the critical Casimir force involving a deformable interface is accurately described by a universal scaling function, the shape of which differs from that one for rigid walls.

19 pages, 11 figures

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Cited by in corpus (4)

• Nonequilibrium fluctuation-induced Casimir pressures in liquid mixtures
• Liquid bridging of cylindrical colloids in near-critical solvents
• Sign change in the net force in sphere-plate and sphere-sphere systems immersed in nonpolar critical fluid due to the interplay between the critical Casimir and dispersion van der Waals forces
• Wetting behavior of a colloidal particle trapped at a composite liquid-vapor interface of a binary liquid mixture