Distinct aggregation patterns and fluid porous phase in a 2D model for colloids with competitive interactions

Bordin, José Rafael

doi:10.1016/j.physa.2017.12.090

Cited by 22 publications

(11 citation statements)

References 65 publications

(91 reference statements)

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“…The clustering was analyzed based in the inter particle bonding. [59][60][61] Two particles in a layer belong to the same cluster if the distance between two of them is shorter than a cutoff 1.3 -a value slightly bigger than the first lenght scale. n c is the number of particles in each cluster, and P (n c ) the probability to find a cluster with size n c .…”

Section: The Model and Simulation Detailsmentioning

confidence: 99%

Hard core-soft shell particles near repulsive interfaces: interplay between adsorption, aggregation and diffusion

Marques,

Bordin

2021

Preprint

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The behavior of colloidal particles with a hard core and a soft shell has attracted the attention for researchers in the physical-chemistry interface not only due the large number of applications, but due the unique properties of these systems in bulk and at interfaces. The adsorption at the boundary of two phases can provide information related to a fluid to clusters transition and with a minima in the contact layer diffusion -and is explained by the competition between the scales in the core-softened interaction. Due the long range repulsion, the particles stay at the distance correspondent to this length scale at low densities, and overcome the repulsive barrier as the packing increases, However, increasing the temperature, the gain in kinetic energy allows the colloids to overcome the long range repulsion barrier even at low densities. As consequence, there is no competition and no maxima was observed in the adsorption.

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Section: The Model and Simulation Detailsmentioning

confidence: 99%

Hard core-soft shell particles near repulsive interfaces: interplay between adsorption, aggregation and diffusion

Marques,

Bordin

2021

Preprint

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“…For example, Liang et al [1] computed the forces (DLVO (Derjaguin-Landau-Verwey-Overbeek) forces) which are applied on colloidal particles in a liquid. Bordin [2] modeled aggregation patterns (self-patterning) in a 2D model for colloids as a function of densities of the suspension and as a function of temperature. Ghosh et al [3] studied the surface wettability of the substrate and its effect on the morphology of the deposited colloidal films.…”

Section: Introductionmentioning

confidence: 99%

Drying of a Colloidal Suspension Deposited on a Substrate: Experimental and Numerical Studies

2021

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We studied a colloidal suspension of polystyrene beads deposited on a glass substrate. The glass substrate contained either straight rough areas on the borders of an open channel or only straight rough areas. The drying of the suspension was observed with an optical microscope, the light bulb of which acted as an energy source to evaporate the suspension. Moreover, the light bulb of the microscope provided optical pressure due to light. We observed that the colloidal particles were trapped on the rough areas of the substrate and not in the open channel at the end of the drying process. In order to understand the experimental results, we modeled numerically the drying of the suspension using a Molecular Dynamics program. The forces imposed on the substrate by the particles are their weight, the optical pressure due to the light bulb of the optical microscope, the attractive Van der Waals force and the repulsive diffuse layer force. The forces acting between two particles are the attractive Van der Waals forces, the repulsive diffuse layer force and the capillary force. The Gaussian random force (linked to Brownian motion) and the particle liquid viscous drag force (also linked to Brownian motion) are horizontal and applied on one particle. The relation between the normal forces N (forces acting by the particles on the substrate) and the horizontal forces F is Amontons' third law of friction F ≤ μk N; in rough areas of the substrate, μk is larger than in smooth areas. This explains that particles are trapped in the areas with high roughness.

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“…Experiments [25] and simulations [26,27] showed that in the case of spherical colloids the mechanism behind the formation of these distinct patterns is the presence of competitive interactions. These com-peting forces can appear from the combination of a short range attraction of the core and a long-range repulsion [28] of the grafted polymers [29][30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Waterlike anomalies in hard core–soft shell nanoparticles using an effective potential approach: Pinned vs adsorbed polymers

Marques

Nogueira

Dillenburg

et al. 2020

Journal of Applied Physics

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In this work, a two dimensional system of polymer grafted nanoparticles is analyzed using largescale Langevin Dymanics simulations. Effective core-softened potentials were obtained for two cases: one where the polymers are free to rotate around the nanoparticle core and a second where the polymers are fixed, with a 45 • angle between them. The use of effective core-softened potentials allow us to explore the complete system phase space. In this way, the P T , T ρ and P ρ phase diagrams for each potential were obtained, with all fluid and solid phases. The phase boundaries were defined analyzing the specific heat at constant pressure, the system mean square displacement, the radial distribution function and the discontinuities in the density-pressure phase diagram. Also, due the competition in the system we have observed the presence of waterlike anomalies, such as the temperature of maximum density -in addition with a tendency of the TMD to move to lower temperatures (negative slope)-and the diffusion anomaly. It was observed different morphologies (stripes, honeycomb, amorphous) for each nanoparticle. We observed that for the fixed polymers case the waterlike anomalies are originated by the competition between the potential characteristic length scales, while for the free to rotate case the anomalies arises due a smaller region of stability in the phase diagram and no competition between the scales was observed.

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Distinct aggregation patterns and fluid porous phase in a 2D model for colloids with competitive interactions

Cited by 22 publications

References 65 publications

Hard core-soft shell particles near repulsive interfaces: interplay between adsorption, aggregation and diffusion

Hard core-soft shell particles near repulsive interfaces: interplay between adsorption, aggregation and diffusion

Drying of a Colloidal Suspension Deposited on a Substrate: Experimental and Numerical Studies

Waterlike anomalies in hard core–soft shell nanoparticles using an effective potential approach: Pinned vs adsorbed polymers

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