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Many-body depletion forces of colloids in a polydisperse polymer dispersant in the long-chain limit

Nguyen, Huy S.; Forsman, Jan LU and Woodward, Clifford E. (2018) In Soft Matter 14(33).
Abstract

We study a system of spherical non-adsorbing particles immersed in a polydisperse polymer fluid. We derive an analytic expression for the many-body depletion interactions between the colloidal particles in the limit of very long chains. We argue that this expression is essentially exact for long chains and justify this using explicit simulations. In this way we are able to elucidate the profound effect of many-body interactions on the particle thermodynamics. We show that using truncated 2-body depletion interactions leads to strong particle segregation, while the complete many-body description predicts that the total depletion force becomes weak so that the system approximates one which interacts via a so-called Kac potential. This... (More)

We study a system of spherical non-adsorbing particles immersed in a polydisperse polymer fluid. We derive an analytic expression for the many-body depletion interactions between the colloidal particles in the limit of very long chains. We argue that this expression is essentially exact for long chains and justify this using explicit simulations. In this way we are able to elucidate the profound effect of many-body interactions on the particle thermodynamics. We show that using truncated 2-body depletion interactions leads to strong particle segregation, while the complete many-body description predicts that the total depletion force becomes weak so that the system approximates one which interacts via a so-called Kac potential. This implies that the depletion interactions can be described using mean-field theory. We show that many-body effects cause a significant contraction of the 2-phase region of the particle dispersion. We also investigate the system approaching the (tricritical) θ point, which terminates the line of first-order critical points of the polymer dispersion in a poor solvent and show that many-body effects suppress particle phase transitions.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Soft Matter
volume
14
issue
33
publisher
Royal Society of Chemistry
external identifiers
  • scopus:85052753441
ISSN
1744-683X
DOI
10.1039/c8sm00631h
language
English
LU publication?
yes
id
0d0e27a1-f054-435c-a15a-82562cb423f8
date added to LUP
2018-10-05 08:32:55
date last changed
2019-02-10 05:08:39
@article{0d0e27a1-f054-435c-a15a-82562cb423f8,
  abstract     = {<p>We study a system of spherical non-adsorbing particles immersed in a polydisperse polymer fluid. We derive an analytic expression for the many-body depletion interactions between the colloidal particles in the limit of very long chains. We argue that this expression is essentially exact for long chains and justify this using explicit simulations. In this way we are able to elucidate the profound effect of many-body interactions on the particle thermodynamics. We show that using truncated 2-body depletion interactions leads to strong particle segregation, while the complete many-body description predicts that the total depletion force becomes weak so that the system approximates one which interacts via a so-called Kac potential. This implies that the depletion interactions can be described using mean-field theory. We show that many-body effects cause a significant contraction of the 2-phase region of the particle dispersion. We also investigate the system approaching the (tricritical) θ point, which terminates the line of first-order critical points of the polymer dispersion in a poor solvent and show that many-body effects suppress particle phase transitions.</p>},
  author       = {Nguyen, Huy S. and Forsman, Jan and Woodward, Clifford E.},
  issn         = {1744-683X},
  language     = {eng},
  month        = {07},
  number       = {33},
  publisher    = {Royal Society of Chemistry},
  series       = {Soft Matter},
  title        = {Many-body depletion forces of colloids in a polydisperse polymer dispersant in the long-chain limit},
  url          = {http://dx.doi.org/10.1039/c8sm00631h},
  volume       = {14},
  year         = {2018},
}