Reentrant network formation in patchy colloidal mixtures under gravity

Heras, Daniel de las; Treffenstädt, Lucas L.; Schmidt, Matthias

doi:10.1103/physreve.93.030601

Cited by 14 publications

(12 citation statements)

References 35 publications

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“…A gravitational field is, in general, unavoidable in sedimentation experiments, and might have a profound effect on colloidal mixtures 34 . For example, in a mixture of patchy colloids with two and three patches (all of the same type) gravity induces the formation of complex sequences in sedimentation-diffusionequilibrium such as the presence of re-entrant percolation 35 .…”

Section: Discussionmentioning

confidence: 99%

Percolation in binary and ternary mixtures of patchy colloids

Seiferling

Heras

Gama

2016

The Journal of Chemical Physics

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We investigate percolation in binary and ternary mixtures of patchy colloidal particles theoretically and using Monte Carlo simulations. Each particle has three identical patches, with distinct species having different types of patch. Theoretically we assume tree-like clusters and calculate the bonding probabilities using Wertheim's first-order perturbation theory for association. For ternary mixtures we find up to eight fundamentally different percolated states. The states differ in terms of the species and pairs of species that have percolated. The strongest gel is a trigel or tricontinuous gel, in which each of the three species has percolated. The weakest gel is a mixed gel in which all of the particles have percolated, but none of the species percolates by itself. The competition between entropy of mixing and internal energy of bonding determines the stability of each state. Theoretical and simulation results are in very good agreement. The only significant difference is the temperature at the percolation threshold, which is overestimated by the theory due to the absence of closed loops in the theoretical description.

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Section: Discussionmentioning

confidence: 99%

Percolation in binary and ternary mixtures of patchy colloids

Seiferling

Heras

Gama

2016

The Journal of Chemical Physics

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“…This results in additional gravity-induced phenomenology not present in bulk systems. Examples are denser particles floating on top of lighter colloids [7], a nematic layer sandwiched by isotropic layers in mixtures of platelets and spheres [8] and mixtures of thin and thick rods [9], and reentrant network formation in mixtures of patchy colloids [10]. It is also common to observe complex stacking sequences in sedimentation with three or more different layers, such as e.g., in mixtures of charged platelets and polymers [11], plate-plate binary systems [12], mixtures of spheres of different sizes [13], and colloidal rod-plate mixtures [14].…”

Section: Introductionmentioning

confidence: 99%

The role of sample height in the stacking diagram of colloidal mixtures under gravity

Geigenfeind¹,

Heras²

2016

J. Phys.: Condens. Matter

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Bulk phase separation is responsible for the occurrence of stacks of different layers in sedimentation of colloidal mixtures. A recently proposed theory (de las Heras and Schmidt 2013 Soft Matter 9 8636) establishes a unique connection between the bulk phase behaviour and sedimentation-diffusion-equilibrium. The theory constructs a stacking diagram of all possible sequences of stacks under gravity in the limit of very high (infinite) sample heights. Here, we study the stacking diagrams of colloidal mixtures at finite sample height, h. We demonstrate that h plays a vital role in sedimentation-diffusion-equilibrium of colloidal mixtures. The region of the stacking diagram occupied by a given sequence of stacks depends on h. Hence, two samples with different heights but identical colloidal concentrations can develop different stacking sequences. In addition, the stacking diagrams for different heights can be qualitatively different since some stacking sequences occur only in a given interval of sample heights. We use the theory to investigate the stacking diagrams of both model bulk systems and mixtures of patchy particles that differ either by the number or by the types of patches.

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“…The percolation is only recovered for very high packing fractions. Previous studies of functionalized colloidal particles have reported also reentrant phenomena driven by, e.g., gravitational fields [33,34], competition between different energy scales [35][36][37], and patches activated by temperature [38].…”

Section: Discussionmentioning

confidence: 99%

Percolation of functionalized colloids on patterned substrates

2018

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We study the percolation properties for a system of functionalized colloids on patterned substrates via Monte Carlo simulations. The colloidal particles are modeled as hard disks with three equally-distributed attractive patches on their perimeter. We describe the patterns on the substrate as circular potential wells of radius Rp arranged in a regular square or hexagonal lattice. We find a nonmonotonic behavior of the percolation threshold (packing fraction) as a function of Rp. For attractive wells, the percolation threshold is higher than the one for clean (non-patterned) substrates if the circular wells are non-overlapping and can only be lower if the wells overlap. For repulsive wells we find the opposite behavior. In addition, at high packing fractions the formation of both structural and bond defects suppress percolation. As a result, the percolation diagram is reentrant with the non-percolated state occurring at very low and intermediate densities.

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Reentrant network formation in patchy colloidal mixtures under gravity

Cited by 14 publications

References 35 publications

Percolation in binary and ternary mixtures of patchy colloids

Percolation in binary and ternary mixtures of patchy colloids

The role of sample height in the stacking diagram of colloidal mixtures under gravity

Percolation of functionalized colloids on patterned substrates

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