Pair Potential of Charged Colloidal Stars

Huang, Fei; Addas, K.; Ward, Andrew; Nt, Flynn; Velasco, Enrique; Hagan, Michael F.; Dogic, Zvonimir; Fraden, Seth

doi:10.1103/physrevlett.102.108302

Cited by 28 publications

(27 citation statements)

References 22 publications

(25 reference statements)

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“…A better understanding for this particular polymer architecture is motivated by emerging applications of branched polyelectrolytes ranging from energy to medicine. 2 Moreover, star polyelectrolytes are also model systems in comparison with block copolymer micelles in aqueous solutions, 19,20 colloids with polymer-grafted chains, 21,22 and semi-flexible filamentous viruses, 23 which all involve polymer chains extending from a central core region.…”

Section: Introductionmentioning

confidence: 99%

Solution properties of star polyelectrolytes having a moderate number of arms

Chremos

Douglas

2017

The Journal of Chemical Physics

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We investigate polyelectrolyte stars having a moderate number of arms by molecular dynamics simulations of a coarse-grained model over a range of polyelectrolyte concentrations, where both the counter-ions and solvent are treated explicitly. This class of polymeric materials is found to exhibit rather distinct static and dynamic properties from linear and highly branched star polyelectrolyte solutions emphasized in past studies. Moderately branched polymers are particle-like in many of their properties, while at the same time they exhibit large fluctuations in size and shape as in the case of linear chain polymers. Correspondingly, these fluctuations suppress crystallization at high polymer concentrations, leading apparently to an amorphous rather than crystalline solid state at high polyelectrolyte concentrations. We quantify the onset of this transition by measuring the polymer size and shape fluctuations of our model star polyelectrolytes and the static and dynamic structure factor of these solutions over a wide range of polyelectrolyte concentration. Our findings for star polyelectrolytes are similar to those of polymer-grafted nanoparticles having a moderate grafting density, which is natural given the soft and highly deformable nature of both of these ‘particles’.

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Section: Introductionmentioning

confidence: 99%

Solution properties of star polyelectrolytes having a moderate number of arms

Chremos

Douglas

2017

The Journal of Chemical Physics

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“…This article aims to address the important issue of the addition of spherical nanoparticles to polydisperse systems of nanorods. The prior experimental literature has raised extensive questions about how the critical concentrations are impacted by the addition of polymeric spheres, particularly in the area of stiff filamentous virus particles, which may even form lamellar, columnar, and smectic phases as a function of sphere concentration as a result of depletion interactions and demixing 4, 14–16. The effects of spheres are particularly important given that many novel nanorod synthesis processes tend to create nanospheres as a side product.…”

Section: Introductionmentioning

confidence: 99%

Isotropic–nematic phase separation and demixing in mixtures of spherical nanoparticles with length‐polydisperse nanorods

Green

2012

J Polym Sci B Polym Phys

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An extension of Onsager theory is developed to simulate isotropic–nematic phase separation in a mixture of spheres with length‐polydisperse system of rods. This work is motivated by recent experimental data on nanorod liquid crystals. Prior theoretical investigations indicate that both polydispersity and the presence of spheres should increase the biphasic–nematic phase transition, that is, the nematic cloud point. Results indicate that the phase diagrams undergo drastic changes depending upon both particle geometry and rod length polydispersity. The key geometric factor is the ratio between the sphere diameter and the rod diameter. In general, length fractionation is enhanced by the addition of spheres, which may be experimentally advantageous for separating short nanorods from a polydisperse population. Simulation results also indicate that the nematic cloud and shadow curves may cross one another because of the scarcity of spheres in the shadow phase. In general, these results do indicate that the nematic cloud point increases as a function of sphere loading; however, in certain areas of phase space, this relationship is nonmonotonic such that the nematic cloud point may actually decrease with the addition of spheres. This work has application to a wide range of nanoparticle systems, including mixtures of spherical nanoparticles with nanorods or nanotubes. Additionally, a number of nonspherical particles and structures may behave as spheres, including crumpled graphene and tightly coiled polymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012

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“…While measurement of the reduction in average spacing for known trap stiffness directly yields the magnitude of the retraction force f = λ, we improved statistics by incorporating the fluctuations around the equilibrium position. Specifically, we experimentally implemented a form of umbrella sampling to measure the free energy, G, of the bundle as a function of R [17,18]. As beads fluctuated in the optical traps [19], we measured their center-to-center separation R and constructed normalized probability distributions: P bundle (R) and P calibration (R) for the bundled and unbundled configurations, respectively ( Fig.…”

mentioning

confidence: 99%

Measuring Cohesion between Macromolecular Filaments One Pair at a Time: Depletion-Induced Microtubule Bundling

Hilitski

Ward

Cajamarca³

et al. 2015

Phys. Rev. Lett.

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In the presence of nonadsorbing polymers, colloidal particles experience ubiquitous attractive interactions induced by depletion forces. Here, we measure the depletion interaction between a pair of microtubule filaments using a method that combines single filament imaging with optical trapping. By quantifying the dependence of filament cohesion on both polymer concentration and solution ionic strength, we demonstrate that the minimal model of depletion, based on the Asakura-Oosawa theory, fails to quantitatively describe the experimental data. By measuring the cohesion strength in two- and three- filament bundles, we verify pairwise additivity of depletion interactions for the specific experimental conditions. The described experimental technique can be used to measure pairwise interactions between various biological or synthetic filaments and complements information extracted from bulk osmotic stress experiments.

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Pair Potential of Charged Colloidal Stars

Cited by 28 publications

References 22 publications

Solution properties of star polyelectrolytes having a moderate number of arms

Solution properties of star polyelectrolytes having a moderate number of arms

Isotropic–nematic phase separation and demixing in mixtures of spherical nanoparticles with length‐polydisperse nanorods

Measuring Cohesion between Macromolecular Filaments One Pair at a Time: Depletion-Induced Microtubule Bundling

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