Particle Diffusion and Crystallisation in Suspensions of Hard Spheres

Megen, W. van; Underwood, S. M.; Müller, Jürgen; Mortensen, T. C.; Henderson, Stuart; Harland, J. L.; Francis, Paul S.

doi:10.1143/ptps.126.171

Cited by 13 publications

(16 citation statements)

References 22 publications

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“…A considerable body of experimental data is now available for crystallization suspensions of particles well represented by hard spheres, largely through the work of the groups of Ackerson 1-3 and van Megen. [4][5][6] These results, as described below, paint a picture considerably more subtle than the standard nucleation-growth-coarsening theories would lead one to expect. Some of this complexity arises from experimental aspects such as polydispersity, gravitational effects, and the degree to which colloidal interactions deviate from that of hard spheres.…”

Section: Introductionmentioning

confidence: 75%

Density functional theory of the kinetics of crystallization of a hard sphere suspension: Coupling structure to density

Wild

Harrowell

2001

The Journal of Chemical Physics

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A theoretical study is presented on the kinetics of crystallization of a colloidal suspension in a fixed volume based upon the use of time dependent density functional theory incorporating conserved particle and nonconserved structure dynamics. This is a continuation of previous work done with conserved particle dynamics alone. The constraints of fixed number and volume lead to nonuniform solutions to the time independent equations of motion. One of the nonuniform solutions is found to have the minimum free energy and is identified as the stable equilibrium coexistence of crystalline and disordered suspension. Numerical integration is used to follow the time dependent motion of a range of initial crystallites. A broadband of stationary states, additional to those identified analytically, are located by the numerical integration. We show that these solutions arise from pinning induced by the discretization of space. The normal and tangential osmotic pressure fields are given and the growing crystallite is shown to be isolated from the higher pressure of the surrounding disordered suspension by the nonequilibrium depletion zone that surrounds it. These results are compared with recent light scattering studies.

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Section: Introductionmentioning

confidence: 75%

Density functional theory of the kinetics of crystallization of a hard sphere suspension: Coupling structure to density

Wild

Harrowell

2001

The Journal of Chemical Physics

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“…Among the phenomena being researched are for example the glass transition 1-4 and particle crystallisation. [5][6][7][8][9] Of special interest are so-called hard sphere like or nearly hard sphere like particles which provide an easy theoretical treatment and easy computer simulations compared to systems with more complex interactions. 10 The most common systems under study are suspensions of sterically stabilised poly-(methylmethacrylate) (PMMA) particles, as a suspension medium, usually a mixture of organic solvents, is used to match the refractive index and the density of the particles to allow measurements using light scattering [11][12][13] and microscopy [14][15][16][17] while avoiding sedimentation.…”

Section: Introductionmentioning

confidence: 99%

On tuning microgel character and softness of cross-linked polystyrene particles

et al. 2017

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Polystyrene (PS) microgel colloids have often been used successfully to model hard sphere behaviour even though the term "gel" invokes inevitably the notion of a more or less soft, deformable object. Here we systematically study the effect of reducing the cross-link density from 1 : 10 (1 cross-link per 10 monomers) to 1 : 100 on particle interactions and "softness". We report on the synthesis and purification of 1 : 10, 1 : 25, 1 : 50, 1 : 75 and 1 : 100 cross-linked PS particles and their characterization in terms of single particle properties, as well as the behaviour of concentrated dispersions. We are able to tune particle softness in the range between soft PNiPAM-microgels and hard PMMA particles while still allowing the mapping of the microgels onto hard sphere behavior with respect to phase diagram and static structure factors. This is mainly due to a rather homogeneous radial distribution of cross-links in contrast to PNiPAM microgels where the cross-link density decreases radially. We find that up to a cross-link density of 1 : 50 particle form factors are perfectly described by a homogeneous sphere model whereas 1 : 75 and 1 : 100 cross-linked spheres are slightly better described as fuzzy spheres. However the fuzziness is rather small compared to typical PNiPAM microgels so that a hard sphere mapping still holds even for these low cross-link densities. Finally, by varying the reaction conditions - changing from batch to semibatch emulsion polymerization and varying the feed rate or by adjusting the monomer to initiator ratio we can tune the fuzziness or significantly alter the inner structure to a more open, star-like architecture.

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“…10, we compare our data for the true (long time) diffusion coefficients with those obtained from experimental results, 35,39,43 and other simulation results from the DPD (Ref. 27) technique.…”

Section: Comparison With Other Resultsmentioning

confidence: 94%

“…27,34,35 For hard particles it is also theoretically expected 36 that for finite concentrations there is also a welldefined short-time diffusion coefficient D S T , which is associated with the time scale separation between local, short-time motion of the colloidal particles and the asymptotic Brownian behavior. The physical explanation for dense systems is that there is a finite amount of free space (unoccupied by other colloids) around each colloid and thus the mobility of the colloids within a short distance (fraction of the colloid radius) is faster than the asymptotic diffusion over a larger distance, which involves the coordinated displacement of several colloids.…”

Section: Short and Long Time Diffusionmentioning

confidence: 96%

Tracer diffusion in colloidal suspensions under dilute and crowded conditions with hydrodynamic interactions

Томилов

Videcoq

Chartier

et al. 2012

The Journal of Chemical Physics

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We consider tracer diffusion in colloidal suspensions under solid loading conditions, where hydrodynamic interactions play an important role. To this end, we carry out computer simulations based on the hybrid stochastic rotation dynamics-molecular dynamics (SRD-MD) technique. Many details of the simulation method are discussed in detail. In particular, our choices for the SRD-MD parameters and for the different scales are adapted to simulating colloidal suspensions under realistic conditions. Our simulation data are compared with published theoretical, experimental and numerical results and compared to Brownian dynamics simulation data. We demonstrate that our SRD-MD simulations reproduce many features of the hydrodynamics in colloidal fluids under finite loading. In particular, finite-size effects and the diffusive behavior of colloids for a range of volume fractions of the suspension show that hydrodynamic interactions are correctly included within the SRD-MD technique.

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Particle Diffusion and Crystallisation in Suspensions of Hard Spheres

Cited by 13 publications

References 22 publications

Density functional theory of the kinetics of crystallization of a hard sphere suspension: Coupling structure to density

Density functional theory of the kinetics of crystallization of a hard sphere suspension: Coupling structure to density

On tuning microgel character and softness of cross-linked polystyrene particles

Tracer diffusion in colloidal suspensions under dilute and crowded conditions with hydrodynamic interactions

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