Structure and aggregation of colloids immersed in critical solvents

Abstract

We consider an ensemble of spherical colloidal particles immersed in a near-critical solvent such as a binary liquid mixture close to its critical demixing point. The emerging long-ranged fluctuations of the corresponding order parameter of the solvent drive the divergence of the correlation length. Spatial confinements of these critical fluctuations by colloidal solute particles, acting as cavities in the fluctuating medium, restrict and modify the fluctuation spectrum in a way which depends on their relative configuration. This results in effective, so-called critical Casimir forces (CCFs) acting on the confining surfaces. Using the available knowledge about CCFs we study the structure and stability of such colloidal suspensions by employing an approach in terms of effective, one-component colloidal systems. Applying the approximation of pairwise additive CCFs we calculate the radial distribution function of the colloids, which is experimentally accessible. We analyze colloidal aggregation due to CCFs and thus allude to previous experimental studies which are still under debate

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Cited by in corpus (10)

• Collective behavior of colloids due to critical Casimir interactions
• Phase behavior of colloidal suspensions with critical solvents in terms of effective interactions
• Many-body effects for critical Casimir forces
• Alignment of cylindrical colloids near chemically patterned substrates induced by critical Casimir torques
• Structure and aggregation of colloids immersed in critical solvents
• Critical Casimir forces along the iso-fields
• Dynamics of colloidal aggregation in microgravity by critical Casimir forces
• Tuning effective interactions close to the critical point in colloidal suspensions
• Liquid bridging of cylindrical colloids in near-critical solvents
• Physical origin of the expansion of polymer coils in a binary solvent in the vicinity of its demixing critical point