Virial coefficients and demixing in the Asakura–Oosawa model

Abstract

The problem of demixing in the Asakura-Oosawa colloid-polymer model is considered. The critical constants are computed using truncated virial expansions up to fifth order. While the exact analytical results for the second and third virial coefficients are known for any size ratio, analytical results for the fourth virial coefficient are provided here, and fifth virial coefficients are obtained numerically for particular size ratios using standard Monte Carlo techniques. We have computed the critical constants by successively considering the truncated virial series up to the second, third, fourth, and fifth virial coefficients. The results for the critical colloid and (reservoir) polymer packing fractions are compared with those that follow from available Monte Carlo simulations in the grand canonical ensemble. Limitations and perspectives of this approach are pointed out. C 2015 AIP Publishing LLC. [http://dx

The Square-Shoulder-Asakura–Oosawa model

“…We called this model the Square-Shoulder-AsakuraOosawa (SSAO) model [27,31,32]. Of course, the more general formulation of the model is when one has σ ss /σ s different from 0, but in this more complicated case of an interacting solvent we would not be able to solve exactly analitically for the effective one-component problem [36].…”

“…with only pairwise interactions. In a fluid binary mixture of small and large non overlapping hard bodies the small particles may induce a depletion entropic attraction between the big particles [27,31,32] when two of these are closer than the dimensions of the small bodies since in this case no small particle fit in the space between the two large particles but there will still be an osmotic pressure due to the small particles surrounding the two big particles pushing them together.…”

Structure, thermodynamic properties, and phase diagrams of few colloids confined in a spherical pore

“…[37] In addition, when σ p /σ is small the main features of the colloid-colloid effective pair poten-tial are similar to the simpler SW potential. Studies of the AO model with different values of diameter ratio have shown interesting properties in bulk, as glassy states and demixing, [38,39] as well as in confinement. [40][41][42] In this work, we study thoroughly highly confined colloids in spherical pores, that show different demeanor as compared to their bulk counterparts.…”

Virial series for inhomogeneous fluids applied to the Lennard-Jones wall-fluid surface tension at planar and curved walls

“…This systems are a mixture of two type of particles with a characteristic big size difference. [9][10][11] Nowadays, virial coefficients and cluster integrals are still under study, even at lower orders. There are several recent works about second order coefficients for diverse systems including inert gases, alkanes, methane in water solution, and polymer solutions.…”

“…[9,10,[12][13][14] Distinct interaction models have been recently analyzed in this context: hard spheres with dipolar momentum, [15][16][17] exponential potential, [18] and the Asakura-Oosawa model for colloids. [9][10][11]19] One of the most studied interaction models for simple fluids is the LJ. Modern studies based on molecular dynamics simulation shed light on its basic properties as viscosity, thermal conductivity, cavitation and melting coexistence.…”