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A simple many-body Hamiltonian for polymer-colloid mixtures: simulations and mean-field theory

Forsman, Jan LU and Woodward, Clifford E. (2012) In Soft Matter 8(7). p.2121-2130
Abstract
We investigate depletion interactions between inert hard colloids in the presence of ideal polymers, with a focus on the case where the polymer radius of gyration (R-g) is equal to the radius of the colloids (R-c). We first establish structure and fluid-fluid phase equilibria of this model system as accurately as possible. To achieve this, we replace the ideal polymers by "effective spheres'', using the approach of Bolhuis and Louis [P. Bolhuis and A. A. Louis, Macromolecules, 2002, 35, 1860.] With this approach, we have been able to simulate (approximate) fluid-fluid phase diagrams in dispersions containing relatively long chains, up to 2401-mers (R-g = R-c = 20 bond lengths). We devote some effort to illustrate many-body effects, and... (More)
We investigate depletion interactions between inert hard colloids in the presence of ideal polymers, with a focus on the case where the polymer radius of gyration (R-g) is equal to the radius of the colloids (R-c). We first establish structure and fluid-fluid phase equilibria of this model system as accurately as possible. To achieve this, we replace the ideal polymers by "effective spheres'', using the approach of Bolhuis and Louis [P. Bolhuis and A. A. Louis, Macromolecules, 2002, 35, 1860.] With this approach, we have been able to simulate (approximate) fluid-fluid phase diagrams in dispersions containing relatively long chains, up to 2401-mers (R-g = R-c = 20 bond lengths). We devote some effort to illustrate many-body effects, and demonstrate that, at least relatively close to the respective critical point, there is a much stronger tendency to form clusters in the low density phase when many-body interactions are taken into account. This is primarily due to the repulsive contributions from higher-order interactions in the liquid, enforcing a high critical polymer chemical potential. At such a high chemical potential, there is a significant tendency to form small clusters in the gas phase. The results of these "effective sphere'' simulations are compared with predictions by a polymer+colloid many-body theory that was recently proposed by us. Our results suggest that this theory, even at the mean-field level is surprisingly accurate. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Soft Matter
volume
8
issue
7
pages
2121 - 2130
publisher
Royal Society of Chemistry
external identifiers
  • wos:000299477300007
  • scopus:84856718071
ISSN
1744-6848
DOI
10.1039/c2sm06737d
language
English
LU publication?
yes
id
72f8c6f1-d8da-48e9-9d27-07b992e801f2 (old id 2425498)
date added to LUP
2012-03-28 09:51:36
date last changed
2017-01-01 05:47:16
@article{72f8c6f1-d8da-48e9-9d27-07b992e801f2,
  abstract     = {We investigate depletion interactions between inert hard colloids in the presence of ideal polymers, with a focus on the case where the polymer radius of gyration (R-g) is equal to the radius of the colloids (R-c). We first establish structure and fluid-fluid phase equilibria of this model system as accurately as possible. To achieve this, we replace the ideal polymers by "effective spheres'', using the approach of Bolhuis and Louis [P. Bolhuis and A. A. Louis, Macromolecules, 2002, 35, 1860.] With this approach, we have been able to simulate (approximate) fluid-fluid phase diagrams in dispersions containing relatively long chains, up to 2401-mers (R-g = R-c = 20 bond lengths). We devote some effort to illustrate many-body effects, and demonstrate that, at least relatively close to the respective critical point, there is a much stronger tendency to form clusters in the low density phase when many-body interactions are taken into account. This is primarily due to the repulsive contributions from higher-order interactions in the liquid, enforcing a high critical polymer chemical potential. At such a high chemical potential, there is a significant tendency to form small clusters in the gas phase. The results of these "effective sphere'' simulations are compared with predictions by a polymer+colloid many-body theory that was recently proposed by us. Our results suggest that this theory, even at the mean-field level is surprisingly accurate.},
  author       = {Forsman, Jan and Woodward, Clifford E.},
  issn         = {1744-6848},
  language     = {eng},
  number       = {7},
  pages        = {2121--2130},
  publisher    = {Royal Society of Chemistry},
  series       = {Soft Matter},
  title        = {A simple many-body Hamiltonian for polymer-colloid mixtures: simulations and mean-field theory},
  url          = {http://dx.doi.org/10.1039/c2sm06737d},
  volume       = {8},
  year         = {2012},
}