Phase behaviour of colloids with short-range repulsions plus nonadsorbing polymer chains

Gruijthuijsen, Kitty van; Tuinier, Remco; Brader, Joseph M.; Stradner, Anna

doi:10.1039/c3sm51432c

Cited by 11 publications

(17 citation statements)

References 35 publications

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“…Equivalently, added repulsions increase the required depletant concentration for phase coexistence. The latter is in qualitative agreement with computer simulations and experimental results for charged nanoparticles in polymeric solutions [16,32,34,35]. Not surprising, the difference in the phase diagram with respect to the HS cases is more dramatic for larger values of |β | and q Y .…”

Section: Complete Phase Diagrams and Critical Pointssupporting

confidence: 88%

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Tuning the phase diagram of colloid-polymer mixtures via Yukawa interactions

García

Tuinier

2016

Phys. Rev. E

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Theory that predicts the phase behavior of interacting Yukawa spheres in a solution containing nonadsorbing polymer is presented. Our approach accounts for multiple overlap of depletion zones. It is found that additional Yukawa interactions beyond hard core interactions strongly affect the location and presence of coexistence regions and phase states. The theoretical phase diagrams are compared with Monte Carlo simulations. The agreement between the two approaches supports the validity of the theoretical approximations made and confirms that, by choosing the parameters of the interaction potentials, tuning of the binodals is possible. The critical end point characterizes the phase diagram topology. It is demonstrated how an additional Yukawa interaction shifts this point with respect to the hard sphere case. Provided a certain depletant-to-colloid size ratio for which a stable colloidal gas-liquid phase coexistence takes place for hard spheres, added direct interactions turn this into a metastable gas-liquid equilibrium. The opposite case, the induction of a stable gas-liquid coexistence where only fluid-solid was present for hard spheres, is also reported.

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Section: Complete Phase Diagrams and Critical Pointssupporting

confidence: 88%

“…However, limited theories are available for dispersed colloidal particles with realistic interactions and added free polymers (acting as depletants). Available approaches focused on short-range repulsive colloids [16,[32][33][34][35]. In real systems, more involved (soft) interactions are often present.…”

Section: Introductionmentioning

confidence: 99%

Tuning the phase diagram of colloid-polymer mixtures via Yukawa interactions

García

Tuinier

2016

Phys. Rev. E

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“…The shaded region indicates the possible extension of the two 20 kDa PEG layers attached to the particle surfaces given by the two extremes, i.e., going from a collapsed state with a spherical diameter of ≈12 nm to a fully extended chain of ≈65 nm. The collapsed state was determined from the previously established empirical relation to estimate the polymer radius of gyration for PEG in water, R g = 6 nm, from the molecular weight . The length of the extended chain was calculated from a monomer length of 0.1464 nm with 20 kDa corresponding to ≈450 monomer units.…”

Section: Resultsmentioning

confidence: 99%

Optical Microrheology of Protein Solutions Using Tailored Nanoparticles

Garting

Stradner

2018

Small

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This work represents a critical re-examination of the application of dynamic light scattering (DLS)-based tracer particle microrheology to measure the zero shear viscosity of aqueous solutions of different proteins up to very high concentrations. It is demonstrated that a combination of surface-functionalized tracer particles, the use of the so-called 3D-DLS technique, and carefully chosen parameters for the scattering experiments is essential for a reliable and artifact-free determination of the viscosity of highly diverse protein solutions, while keeping the amount of protein to a minimum. The major challenges that arise in such microrheology experiments with protein solutions are discussed and used as guiding principles for the synthesis of all-purpose tracer particles with optimal size and an efficient surface functionalization, and the choice of the appropriate amount of tracers in the sample. Potential problems arising from depletion attractions between the tracer particles induced by the proteins are addressed, and compelling evidences for the absence of such effects are presented. The validity of the approach is corroborated by the perfect agreement between the zero shear viscosity obtained from 3D-DLS-based microrheology and literature data from classical rheological measurements for two vastly different protein-solvent systems up to concentrations close to the arrest transition.

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“…The PEG polymers, with a reported molecular weight of 13.3 kg/mol and a polydispersity index of 1.08, were purchased from Polymer Source. We used a previously established empirical relation to estimate the polymer radius of gyration: R g = 47 Å, from the molecular weight 25 . The particles and polymers were prepared by vortex mixing, with salt concentrations in the continuous phase adjusted to 50 mM or 1.5 mM of monovalent salt (NaCl and/or NaN 3 ).…”

Section: Model and Theorymentioning

confidence: 99%

Theoretical predictions of structures in dispersions containing charged colloidal particles and non-adsorbing polymers

Xie

Turesson

Woodward

et al. 2016

Phys. Chem. Chem. Phys.

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We develop a theoretical model to describe structural effects on a specific system of charged colloidal polystyrene particles, upon the addition of non-adsorbing PEG polymers. This system has previously been investigated experimentally, by scattering methods, so we are able to quantitatively compare predicted structure factors with corresponding experimental data. Our aim is to construct a model that is coarse-grained enough to be computationally manageable, yet detailed enough to capture the important physics. To this end, we utilize classical polymer density functional theory, wherein all possible polymer configurations are accounted for, subject to a mean-field Boltzmann weight. We make efforts to counteract drawbacks with this mean-field approach, resulting in structural predictions that agree very well with computationally more demanding simulations. Electrostatic interactions are handled at the fully non-linear Poisson-Boltzmann level, and we demonstrate that a linearization leads to less accurate predictions. The particle charge is an experimentally unknown parameter. We define the surface charge such that the experimental and theoretical gel point at equal polymer concentration coincide. Assuming a fixed surface charge for a certain salt concentration, we find very good agreement between measured and predicted structure factors across a wide range of polymer concentrations. We also present predictions for other structural quantities, such as radial distribution functions, and cluster size distributions. Finally, we demonstrate that our model predicts the occurrence of

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Phase behaviour of colloids with short-range repulsions plus nonadsorbing polymer chains

Cited by 11 publications

References 35 publications

Tuning the phase diagram of colloid-polymer mixtures via Yukawa interactions

Tuning the phase diagram of colloid-polymer mixtures via Yukawa interactions

Optical Microrheology of Protein Solutions Using Tailored Nanoparticles

Theoretical predictions of structures in dispersions containing charged colloidal particles and non-adsorbing polymers

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