Crystallization and gelation in colloidal systems with short-ranged attractive interactions

Fortini, Andrea; Sanz, Eduardo; Dijkstra, Marjolein

doi:10.1103/physreve.78.041402

Cited by 63 publications

(108 citation statements)

References 46 publications

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“…In other words, that quenches were instantaneous. This is typically the case in both experiments [1,3] and computer simulation [1,10,[18][19][20]. Recent developments in controlling colloid-colloid interactions allow the interactions (and thus the effective temperature) to be changed at will, even on timescales much faster than the colloid dynamics, such that controllable quenches may be carried out [21].…”

Section: Introductionmentioning

confidence: 99%

The role of quench rate in colloidal gels

Royall

Malins

2012

Faraday Discuss.

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Interactions between colloidal particles have hitherto usually been fixed by the suspension composition. Recent experimental developments now enable the control of interactions in-situ. Here we use Brownian dynamics simulations to investigate the effect of controlling interactions on gelation, by "quenching" the system from an equilibrium fluid to a gel. We find that, contrary to the normal case of an instantaneous quench, where the local structure of the gel is highly disordered, controlled quenching results in a gel with a higher degree of local order. Under sufficiently slow quenching, local crystallisation is found, which is strongly enhanced when a monodisperse system is used. The higher the degree of local order, the smaller the mean squared displacement, indicating an enhancement of gel stability.

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Section: Introductionmentioning

confidence: 99%

The role of quench rate in colloidal gels

Royall

Malins

2012

Faraday Discuss.

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“…4. Here a bilayer and a micelle merge before the former grows at the expense of the latter.Finally, we note that cluster formation by 'peanuts' whose hydrophilic lobes are of vanishing size proceeds via 'two-step' crystallization [46][47][48][49]: first, dense amorphous blobs nucleate from vapor; second, crystalline order nucleates within these blobs (not shown). We observed a similar dynamics (not shown) for crystal-forming peanuts (see Fig.…”

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confidence: 99%

Self-assembly of amphiphilic peanut-shaped nanoparticles

Whitelam

Bon

2010

The Journal of Chemical Physics

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We use computer simulation to investigate the self-assembly of Janus-like amphiphilic peanut-shaped nanoparticles, finding phases of clusters, bilayers and micelles in accord with ideas of packing familiar from the study of molecular surfactants.However, packing arguments do not explain the hierarchical self-assembly dynamics that we observe, nor the coexistence of bilayers and faceted polyhedra. This coexistence suggests that experimental realizations of our model can achieve multipotent assembly of either of two competing ordered structures.Components are said to 'self-assemble' when they organize to form stable patterns or aggregates without external direction. Self-assembly is driven by interactions as different as weak covalent bonds and capillary forces, involves components ranging in size from Angströms to centimeters, and occurs both in inorganic settings and in living organisms [1][2][3][4][5][6][7][8][9]. Mimicry of the self-assembly seen in the natural world promises the development of new, functional materials patterned on the nanometer scale [10,11]. In pursuit of this goal, we take inspiration from the self-assembly of molecular surfactants to investigate using computer simulation the behavior of a simple model of their colloidal counterparts. Molecular surfactants, comprising chemically linked hydrophobic and hydrophilic groups, are of central importance in biology and industry, able to form a plethora of phases in water or mixtures of water and oily liquids. These phases include micelles [12], bilayers and vesicles, as well as numerous bicontinous phases [13] that serve as internal cellular packaging [14] and are the bane of many a plumber.Here we ask: What might self-assemble in aqueous solution from amphiphilic, peanutshaped colloidal nanoparticles? Such particles can now be prepared in large quantities, starting from spherical, crosslinked polystyrene 'seed' particles of radius ∼ 50 nm. Mixing these seeds with styrene initiates monomer-polymer phase separation and creates particles with a peanut-like shape characterized by two fused spherical lobes of controllable relative size. Additional treatment of the seed particle renders peanuts amphiphilic, with one lobe hydrophobic and the other hydrophilic [15][16][17]; the resulting body can be regarded as a generalized Janus particle [18]. (We note that colloidal silica dumbbells can be synthesized by other routes [19], and that micrometer-scale peanuts show potential as Pickering stabilizers of * swhitelam@lbl.gov arXiv:0907.3227v2 [cond-mat.soft] 19 Feb 2010 2 oil-in-water emulsions [20].) In an attempt to answer our posed question we have constructed a model of interacting peanuts whose minimal character is motivated by the insight into self-assembly afforded by similarly simple model systems [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Our model can be evolved with computational efficiency sufficient to allow observation of collective, thermally-driven dynamics on timescales of seconds. Its construction rests up...

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“…Finally, simulations have also been performed using either the effective one-component depletion potential or the full AO binary mixture. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] Our motivation to carry out the present study rests, however, on different grounds. Three of us have considered fluid-fluid demixing in binary AHS mixtures using the available information on the virial coefficients of those mixtures.…”

Section: Introductionmentioning

confidence: 99%

Virial coefficients and demixing in the Asakura–Oosawa model

Haro

Tejero

Santos

et al. 2015

The Journal of Chemical Physics

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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

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Crystallization and gelation in colloidal systems with short-ranged attractive interactions

Cited by 63 publications

References 46 publications

The role of quench rate in colloidal gels

The role of quench rate in colloidal gels

Self-assembly of amphiphilic peanut-shaped nanoparticles

Virial coefficients and demixing in the Asakura–Oosawa model

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