Depletion Interactions Produced by Nonadsorbing Charged and Uncharged Spheroids

Piech, Martin; Walz, John Y.

doi:10.1006/jcis.2000.7194

Cited by 68 publications

(68 citation statements)

References 60 publications

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“…Recently the depletion potential between two hard spheres due to the presence of hard disclike colloids has been investigated [6,7,8,9]. Subsequently it has been shown within of a free-volume theory that depletion induced phase separation in a colloidal sphere-platelet mixture should occur at low platelet concentrations in systems now experimentally available [10].…”

Section: Introductionmentioning

confidence: 99%

Bulk and wetting phenomena in a colloidal mixture of hard spheres and platelets

Harnau

Dietrich

2005

Phys. Rev. E

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Density functional theory is used to study binary colloidal fluids consisting of hard spheres and thin platelets in their bulk and near a planar hard wall. This system exhibits liquid-liquid coexistence of a phase that is rich in spheres (poor in platelets) and a phase that is poor in spheres (rich in platelets). For the mixture near a planar hard wall, we find that the phase rich in spheres wets the wall completely upon approaching the liquid demixing binodal from the sphere-poor phase, provided the concentration of the platelets is smaller than a threshold value which marks a first-order wetting transition at coexistence. No layering transitions are found in contrast to recent studies on binary mixtures of spheres and non-adsorbing polymers or thin hard rods.

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Section: Introductionmentioning

confidence: 99%

Bulk and wetting phenomena in a colloidal mixture of hard spheres and platelets

Harnau

Dietrich

2005

Phys. Rev. E

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“…Most depletants are spherical, but sometimes depletants with other geometric shapes are utilized, e.g., rods or disks [33,34,[52][53][54][55][56][57][58][59][60][61][62][63][64][65]. Depletant geometry is important.…”

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Tunable depletion potentials driven by shape variation of surfactant micelles

et al. 2016

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“…In this paper we focus on a particular class of entropic interaction, exploring the forces between spheres in a suspension of rodlike particles. This system class has produced a variety of interesting phases [2,3,4], and has stimulated several theoretical models [5,6,7,8,9] and a measurement [10] of the rod-induced depletion interaction.The depletion attraction between two spheres immersed in a dilute suspension of thin rods of length, L c , was first considered by Asakara and Oosawa [11]. Their most important physical insight was that rods in suspension gain both translational and rotational entropy when the sphere surfaces come within L c of one another.…”

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confidence: 99%

Entropic interactions in suspensions of semiflexible rods: Short-range effects of flexibility

2002

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We compute the entropic interactions between two colloidal spheres immersed in a dilute suspension of semi-flexible rods. Our model treats the semi-flexible rod as a bent rod at fixed angle, set by the rod contour and persistence lengths. The entropic forces arising from this additional rotational degree of freedom are captured quantitatively by the model, and account for observations at short range in a recent experiment. Global fits to the interaction potential data suggest the persistence length of fd-virus is about two to three times smaller than the commonly used value of 2.2 µm.PACS numbers: 82.70. Dd, 87.15.La Colloidal dispersions exhibit a fascinating range of equilibrium and non-equilibrium structures, and they have important impact on our daily lives [1]. The interactions between suspension constituents determines the stability of the dispersion against flocculation, and the phase behavior of the colloid. Quantitative models and measurements of these interactions test our basic understanding about these systems, and enable experimenters to better control suspension behaviors and properties. In this paper we focus on a particular class of entropic interaction, exploring the forces between spheres in a suspension of rodlike particles. This system class has produced a variety of interesting phases [2,3,4], and has stimulated several theoretical models [5,6,7,8,9] and a measurement [10] of the rod-induced depletion interaction.The depletion attraction between two spheres immersed in a dilute suspension of thin rods of length, L c , was first considered by Asakara and Oosawa [11]. Their most important physical insight was that rods in suspension gain both translational and rotational entropy when the sphere surfaces come within L c of one another. Subsequent theories computed the attraction more accurately within the Derjaguin approximation [6,7] and beyond [5]. However, in many practical scenarios the rods are not rigid, and current theories do not account for the flexibility of the rods. Indeed, flexibility effects can be important as evidenced by a recent interaction measurement [10] of micron diameter spheres in suspensions of fd-virus; in this case systematic deviations between experiment and "rigid-rod" theories were found at short-range, and were suggested to arise as a result of the flexibility of the fd-virus. Flexible or bent rods have an additional degree of freedom: the rotation about their central axis. As the spheres get closer, this degree of freedom is depleted, the system entropy increases, and the sphere interactions become even more attractive.A quantitative model for this observation is still lacking, and indeed a complete theory of semi-flexible rods near surfaces remains a difficult task. In this paper, we introduce a simple model to compute the depletion potential between two spheres in a dilute solution of semiflexible rods. We use the model to quantitatively explain the experiments of Ref. [10]. The model accounts for the entropic effects of flexibility at short-range, and provi...

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Depletion Interactions Produced by Nonadsorbing Charged and Uncharged Spheroids

Cited by 68 publications

References 60 publications

Bulk and wetting phenomena in a colloidal mixture of hard spheres and platelets

Bulk and wetting phenomena in a colloidal mixture of hard spheres and platelets

Tunable depletion potentials driven by shape variation of surfactant micelles

Entropic interactions in suspensions of semiflexible rods: Short-range effects of flexibility

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