Depletion interactions in colloid-polymer mixtures

Ye, X.; Narayanan, Theyencheri; Tong, Penger; Huang, John S.; Lin, Min; Carvalho, Bruce L.; Fetters, Lewis J.

doi:10.1103/physreve.54.6500

Cited by 111 publications

(166 citation statements)

References 47 publications

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“…The pair potential can, once again, be identified with the depletion potential between two large spheres in a sea of small particles. In the present case the depletion potential is more complicated than that for ideal small particles, where it is simply the Asakura-Oosawa potential (8), and there are no exact results available for arbitrary q and η r 2 . We use an approximation given by Götzelmann et al, which provides an excellent fit to simulation results for the depletion potential for two hard spheres in a sea of small hard spheres for q = 0.1 and reservoir packing fractions η r 2 as large as 0.34 [25].…”

Section: Phase Diagrams Obtained From the Depletion Potentialmentioning

confidence: 98%

“…Static colloid-colloid structure factors S(k) were measured recently in the colloidal liquid phase at triple coexistence, for different size ratios, using a novel application of two-colour dynamic light scattering [7]. There are also recent neutron scattering determinations of S(k) for a series of size ratios and polymer concentrations [8]. The new experimental results [7] motivated Louis et al [9] to calculate the three partial structure factors for the Asakura-Oosawa model using the Percus-Yevick approximation.…”

Section: Introductionmentioning

confidence: 99%

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Phase behaviour and structure of model colloid-polymer mixtures

Dijkstra

Brader

Evans

1999

J. Phys.: Condens. Matter

284

507

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Abstract. We study the phase behaviour and structure of model colloid-polymer mixtures. By integrating out the degrees of freedom of the non-adsorbing ideal polymer coils, we derive a formal expression for the effective one-component Hamiltonian of the colloids. Using the twobody (Asakura-Oosawa pair potential) approximation to this effective Hamiltonian in computer simulations, we determine the phase behaviour for size ratios q = σ p /σ c = 0.1, 0.4, 0.6, and 0.8, where σ c and σ p denote the diameters of the colloids and the polymer coils, respectively. For large q, we find both a fluid-solid and a stable fluid-fluid transition. However, the latter becomes metastable with respect to a broad fluid-solid transition for q 0.4. For q = 0.1 there is a metastable isostructural solid-solid transition which is likely to become stable for smaller values of q. We compare the phase diagrams obtained from simulation with those of perturbation theory using the same effective one-component Hamiltonian and with the results of the free-volume approach. Although both theories capture the main features of the topologies of the phase diagrams, neither provides an accurate description of the simulation results. Using simulation and the Percus-Yevick approximation we determine the radial distribution function g(r) and the structure factor S(k) of the effective one-component system along the fluid-solid and fluid-fluid phase boundaries. At state-points on the fluid-solid boundary corresponding to high colloid packing fractions (packing fractions equal to or larger than that at the triple point), the value of S(k) at its first maximum is close to the value 2.85 given by the Hansen-Verlet freezing criterion. However, at lower colloid packing fractions freezing occurs when the maximum value is much lower than 2.85. Close to the critical point of the fluid-fluid transition we find Ornstein-Zernike behaviour and at very dilute colloid concentrations S(k) exhibits pronounced small-angle scattering which reflects the growth of clusters of the colloids. We compare the phase behaviour of this model with that found in studies of additive binary hard-sphere mixtures.

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Section: Phase Diagrams Obtained From the Depletion Potentialmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Phase behaviour and structure of model colloid-polymer mixtures

Dijkstra

Brader

Evans

1999

J. Phys.: Condens. Matter

284

507

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“…As the Pt/C particles approach each other, the sulphonic acid side chain apposes attraction causing steric repulsion due to the unfavourable decrease in conformational entropy. Colloidal surfaces are thus maintained at distances large enough to damp any attractions due to the depletion effect or London-van der Waals forces and the colloidal suspension is stabilised [27]. Sterically stabilised systems tend to remain stable even at high salt concentrations [28] and conditions were the zeta potentials of the surfaces are reduced to near zero.…”

Section: Catalyst Ink Characterisationmentioning

confidence: 99%

Optimisation of electrophoretic deposition parameters for gas diffusion electrodes in high temperature polymer electrolyte membrane fuel cells

Jao

Pasupathi

Pollet

2013

Journal of Power Sources

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Felix, C. et al. (2013). Optimisation of electrophoretic deposition parameters for gas diffusion electrodes in high temperature polymer electrolyte membrane fuel cells. AbstractElectrophoretic deposition (EPD) method was used to fabricate gas diffusion electrodes (GDEs) for high temperature polymer electrolyte membrane fuel cells (HT PEMFC). Parameters related to the catalyst suspension and the EPD process were studied. Optimum suspension conditions are obtained when the catalyst particles are coated with Nafion ® ionomer and the pH is adjusted to an alkaline range of about 8 e10. These suspensions yield good stability with sufficient conductivity to form highly porous catalyst layers on top of the gas diffusion layers (GDLs). GDEs were fabricated by applying various electric field strengths of which 100 V cm -1 yields the best membrane electrode assembly (MEA) performance. Compared to an MEA fabricated by the traditional hand sprayed (HS) method, the EPD MEA shows superior performance with a peak power increase of about 73% at similar platinum (Pt) loadings. Electrochemical Impedance Spectroscopy (EIS) analysis shows lower charge transfer resistance for the MEA fabricated via the EPD method compared to the HS MEA. The EPD GDE exhibits a greater total pore area (22.46 m 2 g -1 ) compared to the HS GDE (13.43 m 2 g -1 ) as well as better dispersion of the Pt particles within the catalyst layer (CL).

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“…By combining SAXS measurements and numerical simulations, we can also analyze forces present in macromolecule solutions, that is to say the different repulsive and attractive components, and study them as a function of common physico-chemical parameters. This type of approach has already been used in the case of colloid-polymer mixtures (Lutterbach et al, 1999a;Lutterbach et al, 1999b;Ye et al, 1996) or biopolymers (Malfois et al, 1996;Vérétout et al, 1989).…”

Section: Theoretical and Experimental Backgroundmentioning

confidence: 99%

Macromolecular Crystallization Controlled by Colloidal Interactions: The Case of Urate Oxidase

Bonneté¹

2012

Crystallization - Science and Technology

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Depletion interactions in colloid-polymer mixtures

Cited by 111 publications

References 47 publications

Phase behaviour and structure of model colloid-polymer mixtures

Phase behaviour and structure of model colloid-polymer mixtures

Optimisation of electrophoretic deposition parameters for gas diffusion electrodes in high temperature polymer electrolyte membrane fuel cells

Macromolecular Crystallization Controlled by Colloidal Interactions: The Case of Urate Oxidase

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