Complex Self-Assembly from Simple Interaction Rules in Model Colloidal Mixtures

Prestipino, Santi; Gazzillo, Domenico; Munaò, Gianmarco; Costa, Dino

doi:10.1021/acs.jpcb.9b08617

Cited by 8 publications

(12 citation statements)

References 44 publications

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“…The aggregation of colloidal particles is often the outcome of steric stabilization by electrostatic repulsion, which is achieved by modifying the salt concentration or by adding chemicals as stabilizing agents, as in the case of gold colloids [ 2 ] or silica and polystyrene particles [ 3 , 4 ]. The morphology of colloidal aggregates depends on the prevailing aggregation mechanisms and on particle shape [ 1 ], and is typically observed in ramified or compact clusters of fractal dimensionality [ 5 ], in a number of crystalline and amorphous solids [ 6 ], and in mesophases [ 7 , 8 , 9 ], which are partially ordered phases that are intermediate between liquids and crystals (e.g., cluster fluids, liquid crystals, and quasicrystals). Colloidal nanocrystals are even able to self-assemble in crystalline superlattices with an intricate structure [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

Self-Assembled Structures of Colloidal Dimers and Disks on a Spherical Surface

Dlamini

Prestipino

Pellicane

2021

Entropy

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We study self-assembly on a spherical surface of a model for a binary mixture of amphiphilic dimers in the presence of guest particles via Monte Carlo (MC) computer simulation. All particles had a hard core, but one monomer of the dimer also interacted with the guest particle by means of a short-range attractive potential. We observed the formation of aggregates of various shapes as a function of the composition of the mixture and of the size of guest particles. Our MC simulations are a further step towards a microscopic understanding of experiments on colloidal aggregation over curved surfaces, such as oil droplets.

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Section: Introductionmentioning

confidence: 99%

Self-Assembled Structures of Colloidal Dimers and Disks on a Spherical Surface

Dlamini

Prestipino

Pellicane

2021

Entropy

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“…As a preliminary consideration, since spheres are noninteracting beyond the hard core, it is not straightforward to associate d bond with the range of attractive interactions, as is commonly assumed in studies of SALR fluids. In our previous analysis, 24 two spheres were considered as bonded together when their distance is smaller than σ 3 + 3σ 1 ≡ 2σ 2 , which represents -according to Eq. ( 1) -the maximum distance at which two spheres can experience a mutual attraction mediated by a small monomer placed in the middle.…”

Section: Resultsmentioning

confidence: 99%

“…[18][19][20] Recently, we have undertaken an extended investigation of the phase behavior of a dilute colloidal mixture of Janus dimers and spherical particles, by means of computer simulation. [21][22][23][24] In our scheme, a dimer is modeled as a pair of tangent hard spheres of different size, while the other species is represented by a hard sphere. Beside the steric repulsion, the two species interact via a square-well attraction between small monomers and spheres.…”

Section: Introductionmentioning

confidence: 99%

“…We take the square-well width to be small compared to the size of spheres, as is usual for colloidal systems, but at the same time large enough to allow for the formation of aggregates of dimers and spheres at low temperature. 24 Moreover, the absence of any dimer-dimer or sphere-sphere attraction reflects the implicit assumption that this kind of interaction is significantly weaker that the dimer-sphere attraction. Finally, the significant size asymmetry between the monomers constituting the dimers favors the encapsulation of spheres.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, liquid-vapor separation is preempted by the formation of supramolecular aggregates. We have documented a rich phase scenario arising for our mixture, in terms of diameter and concentration of spheres: 24 when the two species have similar sizes and the concentration is small, we observe the onset of small clusters of spheres covered by a layer of dimers; for larger concentrations, we find other selfassembled structures (i.e. gel-like networks and bilayers); finally, when spheres are substantially larger than dimers, we observe the formation of membranes (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Early stages of aggregation in fluid mixtures of dimers and spheres: a theoretical and simulation study

Munaò,

Prestipino,

Costa

2021

Preprint

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We use Monte Carlo simulation and the Reference Interaction Site Model (RISM) theory of molecular fluids to investigate a simple model of colloidal mixture consisting of dimers, made up of two tangent hard monomers of different size, and hard spheres. In addition to steric repulsion, the two species interact via a square-well attraction only between small monomers and spheres. Recently, we have characterized the low-temperature regime of this mixture by Monte Carlo, reporting on the spontaneous formation of a wide spectrum of supramolecular aggregates [Prestipino et al, J. Phys. Chem. B, 2019, 123, 9272]. Here we focus on a regime of temperatures where, on cooling, the appearance of local inhomogeneties first, and the early stages of aggregation thereafter, are observed. In particular, we find signatures of aggregation in the onset of a low-wavevector peak in the structure factors of the mixture, as computed by both theory and simulation. Then, we link the structural information to the microscopic arrangement through a detailed cluster analysis of Monte Carlo configurations. In this regard, we devise a novel method to compute the maximum distance for which two spheres can be regarded as bonded together, a crucial issue in the proper identification of fluid aggregates. The RISM theory provides relatively accurate structural and thermodynamic predictions in comparison with Monte Carlo, but with slightly degrading performances as the fluid progresses inside the locally inhomogeneous phase. Our study certifies the efficacy of the RISM approach as a useful complement to numerical simulation for a reasoned analysis of aggregation properties in colloidal mixtures.Recent studies have shown that a rich variety of mesoscopic patterns are obtained for asymmetrically-shaped particles whose constituent blocks interact through spherically-symmetric potentials. [1][2][3][4] In this regard, a versatile model is represented by Janus dimers, i.e. heteronuclear dimers in which one monomer is solvophilic and the other one is solvophobic. 5,6 The interest in this specific class of colloidal particles stems from their capability to be synthesized in a large variety of sizes, aspect ratios, and interaction properties, 7-11 and from their high technological im-

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Clustering in Mixtures of SALR Particles and Hard Spheres with Cross Attraction

et al. 2022

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Self-assembling complex fluids are often modeled as particles with effective competing isotropic interactions, combining a short-range attraction (SA) followed by a longer-range repulsion (LR). For moderately low temperatures and densities, SALR particles form clusters in equilibrium, at least provided that the potential parameters are appropriate. Here we inquire into the possibility that cluster formation in SALR fluids might be pushed by a foreign species even under thermodynamic conditions that would not allow for clusterization of the pure system. To this aim, we study by Monte Carlo simulations a mixture of hard-sphere two-Yukawa particles and hard spheres, with a cross interaction modeled by a square-well attraction, and we investigate the conditions of clustering in terms of strength of attraction and relative concentration of the two species. We find that clusters can occur in the mixture for the same temperature and density where the pure SALR fluid is almost structureless. In particular, we single out a cross attraction such that clusters are formed with a SALR concentration as low as 5%. We also find a situation where nearly pure droplets of hard spheres are held together by a shell of SALR particles. Conversely, we show that clustering can be undermined in the mixture under conditions for which this process takes place in the parent SALR fluid. Using a simple criterion, based on the second virial coefficients of the attractive part of interaction potentials (the so-called “reference attractive fluids”), we are able to predict accurately whether clustering is favored (or hindered) in the mixture, as compared to the pure SALR fluid.

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Complex Self-Assembly from Simple Interaction Rules in Model Colloidal Mixtures

Cited by 8 publications

References 44 publications

Self-Assembled Structures of Colloidal Dimers and Disks on a Spherical Surface

Self-Assembled Structures of Colloidal Dimers and Disks on a Spherical Surface

Early stages of aggregation in fluid mixtures of dimers and spheres: a theoretical and simulation study

Clustering in Mixtures of SALR Particles and Hard Spheres with Cross Attraction

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