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Simulating equilibrium surface forces in polymer solutions using a canonical grid method

Turesson, Martin LU ; Woodward, Clifford E.; Åkesson, Torbjörn LU and Forsman, Jan LU (2008) In The Journal of Physical Chemistry Part B 112(32). p.9802-9809
Abstract
A new simulation method for nonuniform polymer solutions between planar surfaces at full chemical equilibrium is described. The technique uses a grid of points in a two-dimensional thermodynamic space, labeled by surface area and surface separations. Free energy differences between these points are determined via Bennett's optimized rates method in the canonical ensemble. Subsequently, loci of constant chemical potential are determined within the grid via simple numerical interpolation. In this way, a series of free energy versus separation curves are determined for a number of different chemical potentials. The method is applied to the case of hard sphere polymers between attractive surfaces, and its veracity is confirmed via comparisons... (More)
A new simulation method for nonuniform polymer solutions between planar surfaces at full chemical equilibrium is described. The technique uses a grid of points in a two-dimensional thermodynamic space, labeled by surface area and surface separations. Free energy differences between these points are determined via Bennett's optimized rates method in the canonical ensemble. Subsequently, loci of constant chemical potential are determined within the grid via simple numerical interpolation. In this way, a series of free energy versus separation curves are determined for a number of different chemical potentials. The method is applied to the case of hard sphere polymers between attractive surfaces, and its veracity is confirmed via comparisons with established alternative simulation techniques, namely, the grand canonical ensemble and isotension ensemble methods. The former method is shown to fail when the degree of polymerization is too large. An interesting interplay between repulsive steric interactions and attractive bridging forces occurs as the surface attraction and bulk monomer density are varied. This behavior is further explored using polymer density functional theory, which is shown to be in good agreement with the simulations. Our results are also discussed in light of recent self-consistent field calculations which correct the original deGennes results for infinitely Iona polymers. In particular, we look at the role of chain ends by investigating the behavior of ring polymers. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
112
issue
32
pages
9802 - 9809
publisher
The American Chemical Society
external identifiers
  • wos:000258290000030
  • scopus:50549086833
ISSN
1520-5207
DOI
10.1021/jp8020529
language
English
LU publication?
yes
id
5c54c35a-0fe1-4f7e-8d0b-0a2f2550d4c8 (old id 1252757)
date added to LUP
2008-11-17 15:01:46
date last changed
2017-01-01 06:16:25
@article{5c54c35a-0fe1-4f7e-8d0b-0a2f2550d4c8,
  abstract     = {A new simulation method for nonuniform polymer solutions between planar surfaces at full chemical equilibrium is described. The technique uses a grid of points in a two-dimensional thermodynamic space, labeled by surface area and surface separations. Free energy differences between these points are determined via Bennett's optimized rates method in the canonical ensemble. Subsequently, loci of constant chemical potential are determined within the grid via simple numerical interpolation. In this way, a series of free energy versus separation curves are determined for a number of different chemical potentials. The method is applied to the case of hard sphere polymers between attractive surfaces, and its veracity is confirmed via comparisons with established alternative simulation techniques, namely, the grand canonical ensemble and isotension ensemble methods. The former method is shown to fail when the degree of polymerization is too large. An interesting interplay between repulsive steric interactions and attractive bridging forces occurs as the surface attraction and bulk monomer density are varied. This behavior is further explored using polymer density functional theory, which is shown to be in good agreement with the simulations. Our results are also discussed in light of recent self-consistent field calculations which correct the original deGennes results for infinitely Iona polymers. In particular, we look at the role of chain ends by investigating the behavior of ring polymers.},
  author       = {Turesson, Martin and Woodward, Clifford E. and Åkesson, Torbjörn and Forsman, Jan},
  issn         = {1520-5207},
  language     = {eng},
  number       = {32},
  pages        = {9802--9809},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Simulating equilibrium surface forces in polymer solutions using a canonical grid method},
  url          = {http://dx.doi.org/10.1021/jp8020529},
  volume       = {112},
  year         = {2008},
}