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

Xie, Fei LU ; Turesson, Martin LU ; Woodward, Clifford E.; Van Gruijthuijsen, Kitty; Stradner, Anna LU and Forsman, Jan LU (2016) In Physical Chemistry Chemical Physics 18(16). p.11422-11434
Abstract

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... (More)

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 agreements 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 equilibrium clusters at high polymer concentrations, but low particle volume fractions and salt levels.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Chemistry Chemical Physics
volume
18
issue
16
pages
13 pages
publisher
The Royal Society of Chemistry
external identifiers
  • Scopus:84967139742
  • WOS:000374786300083
ISSN
1463-9076
DOI
10.1039/c5cp07814h
language
English
LU publication?
yes
id
02a6ac40-92f2-4ea2-8203-359acbff073a
date added to LUP
2016-09-30 07:53:07
date last changed
2017-01-01 08:35:34
@article{02a6ac40-92f2-4ea2-8203-359acbff073a,
  abstract     = {<p>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 agreements 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 equilibrium clusters at high polymer concentrations, but low particle volume fractions and salt levels.</p>},
  author       = {Xie, Fei and Turesson, Martin and Woodward, Clifford E. and Van Gruijthuijsen, Kitty and Stradner, Anna and Forsman, Jan},
  issn         = {1463-9076},
  language     = {eng},
  month        = {04},
  number       = {16},
  pages        = {11422--11434},
  publisher    = {The Royal Society of Chemistry},
  series       = {Physical Chemistry Chemical Physics},
  title        = {Theoretical predictions of structures in dispersions containing charged colloidal particles and non-adsorbing polymers},
  url          = {http://dx.doi.org/10.1039/c5cp07814h},
  volume       = {18},
  year         = {2016},
}