TITLE

Entropy driven demixing in fluids of rigidly ordered particles

AUTHOR(S)
DuBois, Sylviane; Perera, Aure´lien
PUB. DATE
April 2002
SOURCE
Journal of Chemical Physics;4/8/2002, Vol. 116 Issue 14, p6354
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
The entropy driven demixing in binary mixtures of rigidly ordered hard particles is studied herein. To that end, a free energy functional for this type of system, as well as an approximation for the corresponding pair direct correlation function, are proposed. The accuracy of the functional is first tested by computing the pressure for previously studied similar systems. The spinodal of the fluid-fluid separation is studied, and shown to be a loop in the (ρ[sub 1],ρ[sub 2]) density-density phase diagram, with both a lower and an upper critical point. This feature is strikingly different from what is observed in the demixing of disordered mixtures, where only a lower critical point is generally found. The influence of molecular shape is equally studied, by varying geometric properties such as convexity, aspect and breadth ratios as well as by mixing prolate and oblate shapes. Within the present theory, demixing is forbidden for mixtures of hard spheres and mixtures of prolate (oblate) shapes with the same breadth, irrespective of their aspect ratios. Demixing is enhanced for mixtures of prolates and oblates and more generally for large asymmetry in the particles breadths. The proposed functional is built such that it reduces to the correct Onsager limit when very large aspect ratios are considered. However, the Onsager second virial approximation, when applied to cases of moderate to small aspect ratios, differs from the present theory, as it can only exhibit demixing with a lower critical point.
ACCESSION #
6407946

 

Related Articles

  • Phase behavior of symmetric rod–plate mixtures revisited: Biaxiality versus demixing. Varga, Szabolcs; Galindo, Amparo; Jackson, George // Journal of Chemical Physics;12/8/2002, Vol. 117 Issue 22, p10412 

    The phase behavior of symmetric binary rod-plate mixtures has been investigated by numerical minimization of a free energy functional derived by Parsons [J. D. Parsons, Phys. Rev. A 19, 1225 (1979)] and Lee [S. D. Lee, J. Chem. Phys. 87, 4972 (1987)]. Both rod and plate molecules are represented...

  • BIFURCATION ANALYSIS OF A TWO-DIMENSIONAL BINARY MIXTURE OF HARD NEEDLES. CHRZANOWSKA, AGNIESZKA // Acta Physica Polonica B;2013, Vol. 44 Issue 1, p91 

    Bifurcation analysis of a two-dimensional binary mixture of hard needles, which due to the second order of the transition character gives directly the density of the transitions, thus the phase diagram, has been performed for a complete set of the compositions and the needles lengths ratios...

  • Thermal, spectroscopic, and dissolution studies of the simvastatin-acetylsalicylic acid mixtures. Górniak, Agata; Karolewicz, Bożena; Żurawska-Płaksej, Ewa; Pluta, Janusz // Journal of Thermal Analysis & Calorimetry;Mar2013, Vol. 111 Issue 3, p2125 

    The objective of the present investigation was to study the effect of eutectic formation on in vitro dissolution of simvastatin (SIM) released from mixtures with acetylsalicylic acid (ASA) prepared by a grinding method. SIM-ASA mixtures were characterized by means of differential scanning...

  • The phase behavior of two-dimensional symmetrical mixtures in a weak external field of square symmetry. Materniak, S.; Patrykiejew, A.; Sokołowski, S. // Journal of Chemical Physics;6/7/2011, Vol. 134 Issue 21, p214705 

    Using Monte Carlo simulation methods in the grand canonical and semigrand canonical ensembles, we study the phase behavior of two-dimensional symmetrical binary mixtures of Lennard-Jones particles subjected to a weakly corrugated external field of a square symmetry. It is shown that the both...

  • Electrostatics and aggregation: How charge can turn a crystal into a gel. Schmit, Jeremy D.; Whitelam, Stephen; Dill, Ken // Journal of Chemical Physics;8/28/2011, Vol. 135 Issue 8, p085103 

    The crystallization of proteins or colloids is often hindered by the appearance of aggregates of low fractal dimension called gels. Here we study the effect of electrostatics upon crystal and gel formation using an analytic model of hard spheres bearing point charges and short range attractive...

  • Fluctuations and phase diagrams in ternary mixtures. Teubner, Max // Journal of Chemical Physics;3/15/1991, Vol. 94 Issue 6, p4490 

    A binary or liquid ternary mixture has two independent densities, say x1 and x2. There are three independent fluctuations in these densities, namely 〈(δx1)2>, 〈(δx2)2>, and 〈δx1 δx2>. It is demonstrated that there exists a homogeneous linear relation between these...

  • Phase coexistence in polydisperse liquid mixtures: Beyond the van der Waals approximation. Kalyuzhnyi, Yurij V.; Kahl, Gerhard // Journal of Chemical Physics;10/8/2003, Vol. 119 Issue 14, p7335 

    The solution of the mean spherical approximation for a polydisperse fluid mixture of particles interacting via a set of (factorizable) hard-sphere Yukawa potentials allows one to represent those thermodynamic quantities that are relevant to determine phase coexistence (i.e., pressure and...

  • Core-softened potentials and the anomalous properties of water. Jagla, E. A. // Journal of Chemical Physics;11/15/1999, Vol. 111 Issue 19, p8980 

    Studies the phase diagram of a system of spherical particles interacting in three dimensions through a potential consisting of a strict hard core plus a linear repulsive shoulder at larger distances. Anomalous properties of the phase diagram similar to those observed in water; Maxima of density...

  • Solid–liquid phase diagrams of binary mixtures. Campanella, Luigi; Micieli, Valentina; Tomassetti, Mauro; Vecchio, Stefano // Journal of Thermal Analysis & Calorimetry;Mar2010, Vol. 99 Issue 3, p887 

    This study reports the investigation of three binary mixtures represented by acetylsalicylic acid (ASA) with its most important degradation product, salicylic acid (SA), and two of the most commonly used excipients (polyethylene glycol 4000 (PEG-4000) and d-mannitol (MA)). The liquidus and...

Share

Read the Article

Courtesy of VIRGINIA BEACH PUBLIC LIBRARY AND SYSTEM

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics