Tuning effective interactions close to the critical point in colloidal suspensions

Abstract

We report a numerical investigation of two colloids immersed in a critical solvent, with the aim of quantifying the effective colloid-colloid interaction potential. By turning on an attraction between the colloid and the solvent particles we follow the evolution from the case in which the solvent density close to the colloids changes from values smaller than the bulk to values larger than the bulk. We thus effectively implement the so-called $(+,+)$ and $(-,-)$ boundary conditions defined in field theoretical approaches focused on the description of critical Casimir forces. We find that the effective potential at large distances decays exponentially, with a characteristic decay length compatible with the bulk critical correlation length, in full agreement with theoretical predictions. We also investigate the case of $(+,-)$ boundary condition, where the effective potential becomes repulsive. Our study provides a guidance for a design of the interaction potential which can be exploited to control the stability of colloidal systems.

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Cited by in corpus (8)

• Tunable long range forces mediated by self-propelled colloidal hard spheres
• Collective behavior of colloids due to critical Casimir interactions
• Casimir-like forces at the percolation transition
• Depletion force in the infinite-dilution limit in a solvent of nonadditive hard spheres
• Effective potentials induced by mixtures of patchy and hard co-solutes
• Solvent mediated forces in critical fluids
• The square lattice Ising model on the rectangle III: Hankel and Toeplitz determinants
• Discontinuous change from thermally- to geometrically- dominated effective interactions in colloidal solutions