How soft repulsion enhances the depletion mechanism

Abstract

We investigate binary mixtures of large colloids interacting through soft potentials with small, ideal depletants. We show that softness has a dramatic effect on the resulting colloid-colloid effective potential when the depletant-to-colloid size ratio $q$ is small, with significant consequences on the colloidal phase behaviour. We also provide an exact relation that allows us to obtain the effective pair potential for {\it any} type of colloid-depletant interactions in the case of ideal depletants, without having to rely on complicated and expensive full-mixture simulations. We also show that soft repulsion among depletants further enhances the tendency of colloids to aggregate. Our theoretical and numerical results demonstrate that --- in the limit of small $q$ --- soft mixtures cannot be mapped onto hard systems and hence soft depletion is not a mere extension of the widely used Asakura-Oosawa potential.

Accepted for publication in Soft Matter

References in corpus (7)

• Entropically Driven Helix Formation
• Gelation as arrested phase separation in short-ranged attractive colloid-polymer mixtures
• How to derive and parameterize effective potentials in colloid-polymer mixtures
• Statics and Dynamics of Colloid-Polymer Mixtures Near Their Critical Point of Phase Separation: A Computer Simulation Study of a Continuous AO Model
• Viscoelasticity and Stokes-Einstein relation in repulsive and attractive colloidal glasses
• Critical Casimir forces and colloidal aggregation: A numerical study
• Monte Carlo cluster algorithm for fluid phase transitions in highly size-asymmetrical binary mixtures

Cited by in corpus (6)

• A new look at effective interactions between microgel particles
• Bridging and depletion mechanisms in colloid-colloid effective interactions: A reentrant phase diagram
• Simple analysis of scattering data with Ornstein-Zernike equation
• Phase Behaviour of Binary Hard-Sphere Mixtures: Free Volume Theory Including Reservoir Hard-Core Interactions
• Virial coefficients and demixing in the Asakura-Oosawa model
• Effective potentials induced by mixtures of patchy and hard co-solutes