Interactions between Spheroidal Colloidal Particles

Schiller, P.; Krüger, Sven; Wahab, M.; Mögel, H.-J.

doi:10.1021/la2015918

Cited by 31 publications

(36 citation statements)

References 21 publications

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“…In this case √ λ 1 λ 2 = √2 r rod , where r rod is the radius of rods. The net interaction including van der Waals attraction and electrostatic repulsion is given by 54 …”

Section: Methodsmentioning

confidence: 99%

Aggregation of Elongated Colloids in Water

Ortiz

Jerolmack

2017

Langmuir

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Colloidal aggregation is a canonical example of disordered growth far from equilibrium and has been extensively studied for the case of spherical monomers. Many particles encountered in industry and the environment are highly elongated; however, the control of particle shape on aggregation kinetics and structure is not well-known. Here, we explore this control in laboratory experiments that document aqueous diffusion and aggregation of two different elongated colloids: natural asbestos fibers and synthetic glass rods, with similar aspect ratios of about 5:1. We also perform control runs with glass spheres of similar size (∼1 μm). The aggregates assembled from the elongated particles are noncompact, with morphologies and growth rates that differ markedly from the classical aggregation dynamics observed for spherical monomers. The results for asbestos and glass rods are remarkably similar, demonstrating the primacy of shape over material properties—suggesting that our findings may be extended to other elongated colloids such as carbon nanotubes/fibers. This study may lead to enhanced prediction of the transport and fate of colloidal contaminants in the environment, which are strongly influenced by the growth and structure of aggregates.

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“…In this case √ λ 1 λ 2 = √2 r rod , where r rod is the radius of rods. The net interaction including van der Waals attraction and electrostatic repulsion is given by 54 …”

Section: Methodsmentioning

confidence: 99%

Aggregation of Elongated Colloids in Water

Ortiz

Jerolmack

2017

Langmuir

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“…Having elucidated the nature of facilitated dynamics in the case of ellipsoids with short-ranged repulsions, we turn our attention to the influence of attractive depletion interactions on glass formation. Depletion interactions between particles are known to depend on local curvature (35,36). For ellipsoids, therefore, these interactions are anisotropic and favor the alignment of particles along their major axis (33).…”

Section: Spatial Decoupling Of Dhs and Prediction Of Reentrant Glassmentioning

confidence: 99%

Dynamical facilitation governs glassy dynamics in suspensions of colloidal ellipsoids

Mishra¹,

Nagamanasa²,

Ganapathy

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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One of the greatest challenges in contemporary condensed matter physics is to ascertain whether the formation of glasses from liquids is fundamentally thermodynamic or dynamic in origin. Although the thermodynamic paradigm has dominated theoretical research for decades, the purely kinetic perspective of the dynamical facilitation (DF) theory has attained prominence in recent times. In particular, recent experiments and simulations have highlighted the importance of facilitation using simple model systems composed of spherical particles. However, an overwhelming majority of liquids possess anisotropy in particle shape and interactions, and it is therefore imperative to examine facilitation in complex glass formers. Here, we apply the DF theory to systems with orientational degrees of freedom as well as anisotropic attractive interactions. By analyzing data from experiments on colloidal ellipsoids, we show that facilitation plays a pivotal role in translational as well as orientational relaxation. Furthermore, we demonstrate that the introduction of attractive interactions leads to spatial decoupling of translational and rotational facilitation, which subsequently results in the decoupling of dynamical heterogeneities. Most strikingly, the DF theory can predict the existence of reentrant glass transitions based on the statistics of localized dynamical events, called excitations, whose duration is substantially smaller than the structural relaxation time. Our findings pave the way for systematically testing the DF approach in complex glass formers and also establish the significance of facilitation in governing structural relaxation in supercooled liquids.glass transition | dynamical facilitation | anisotropic colloids T he transformation of liquids into glasses is as ubiquitous as it is enigmatic. From the formation of obsidian during volcanic eruptions (1) and fabrication of superstrong metallic glasses (2) to exotic forms of slow dynamics in crystals of colloidal dimers (3) and Janus particles (4), glass formation pervades nature, industry, and academia. A vast majority of molecular glass-forming materials exhibit anisotropy in shape and interparticle interactions, which often has a profound influence on their glassy dynamics. The rapidly expanding repertoire of chemists has made it possible to design colloidal particles of desired shape and interactions that can serve as realistic experimental analogs of these molecular liquids (5). By contrast, prominent theories like the Adam-Gibbs (6) theory, random first-order transition (RFOT) theory (7,8), and the dynamical facilitation (DF) theory (9, 10) have been tested predominantly on spherical glass formers with isotropic interactions, which exhibit gross features of glassy dynamics, but fail to capture the nuances of vitrification in complex systems.The discovery of growing static (11-16) and dynamic (17-21) length scales appears to support the thermodynamic perspective of the Adam-Gibbs and RFOT theories. However, the growth in static length scales over the dynami...

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“…For nonspherical shapes, the screened-electrostatic pair interaction is only analytically known in a few cases for all particle configurations, even within linear screening theory. However, some studies exist for disks [35][36][37][38], rods [39,40], spheroids [41][42][43][44][45], or helices [46], where the potential is sometimes calculated only for infinitely long, thin, or ion-penetrable particles, restricted particle configurations, or orientation-averaged interactions [47]. The difficulty in finding analytical solutions lies in the finite ion-impenetrable particle volume which complicates matching the series expansion solution (if it is even available for the geometry under consideration) of the unscreened potential inside and the screened potential outside the particle via the boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

Screened Coulomb interactions of general macroions with nonzero particle volume

Everts

2020

Phys. Rev. Research

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A semianalytical approach is developed to calculate the effective pair potential of rigid arbitrarily shaped macroions with a nonvanishing particle volume, valid within linear screening theory and the mean-field approximation. The essential ingredient for this framework is a mapping of the particle to a singular charge distribution with adjustable effective charge and shape parameters determined by the particle surface electrostatic potential. For charged spheres, this method reproduces the well-known Derjaguin-Landau-Verwey-Overbeek (DLVO) potential. Further exemplary benchmarks of the method for more complicated cases, like tori, triaxial ellipsoids, and additive torus-sphere mixtures, leads to accurate closed-form integral expressions for all particle separations and orientations. The findings are relevant for determining the phase behavior of macroions with experiments and simulations for various particle shapes.

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Interactions between Spheroidal Colloidal Particles

Cited by 31 publications

References 21 publications

Aggregation of Elongated Colloids in Water

Aggregation of Elongated Colloids in Water

Dynamical facilitation governs glassy dynamics in suspensions of colloidal ellipsoids

Screened Coulomb interactions of general macroions with nonzero particle volume

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