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Surface forces at restricted equilibrium, in solutions containing finite or infinite semiflexible polymers

Forsman, Jan LU and Woodward, Clifford E. (2007) In Macromolecules 40(23). p.8396-8408
Abstract
We use density functional theory to investigate how the presence of polymers influence the interactions between adsorbing or nonadsorbing flat surfaces, forming a slit geometry. The study is primarily made under "restricted equilibrium" conditions, i.e., below a threshold separation, the chains are allowed to equilibrate conformationally between the surfaces, but they are unable to diffuse into or out from the slit. This is believed to be a reasonable model for commonly encountered experimental situations, when the surfaces are large and adsorbing and the polymers are long. Using a recently presented density functional theory, we are able to compare predictions for chains of finite and infinite length. A major advantage of the infinite... (More)
We use density functional theory to investigate how the presence of polymers influence the interactions between adsorbing or nonadsorbing flat surfaces, forming a slit geometry. The study is primarily made under "restricted equilibrium" conditions, i.e., below a threshold separation, the chains are allowed to equilibrate conformationally between the surfaces, but they are unable to diffuse into or out from the slit. This is believed to be a reasonable model for commonly encountered experimental situations, when the surfaces are large and adsorbing and the polymers are long. Using a recently presented density functional theory, we are able to compare predictions for chains of finite and infinite length. A major advantage of the infinite chain formulation is that it is a high resolution theory, and predictions from the finite length version will exactly approach the ones for infinite chains, when the degree of polymerization becomes large enough. Our study spans across a relatively large number of relevant system parameters, such as bulk concentration, surface adsorption strength, polymer length, and chain flexibility. The response in terms of the net surface interaction, to a change of a system parameter, is often nonmonotonic. We also make comparisons with predictions it full equilibrium, where the diffusion constraint has been relaxed. We give a specific example of how a diffusion-limited process can lead to hysteresis effects, similar to those observed in many surface force measurements. Finally, in a separate section of this work, we have included some direct experimental comparisons, demonstrating the relevance and applicability of restricted equilibrium conditions to "real world" scenarios. The computational power of the density functional approach is here highlighted, with calculations including semiflexible 20000-mers. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Macromolecules
volume
40
issue
23
pages
8396 - 8408
publisher
The American Chemical Society
external identifiers
  • wos:000250801700040
  • scopus:36349002935
ISSN
0024-9297
DOI
10.1021/ma071181t
language
English
LU publication?
yes
id
f7a7d8dd-7464-460e-be4f-decb7bb5d4fd (old id 971855)
date added to LUP
2008-01-29 15:05:28
date last changed
2017-01-01 04:21:26
@article{f7a7d8dd-7464-460e-be4f-decb7bb5d4fd,
  abstract     = {We use density functional theory to investigate how the presence of polymers influence the interactions between adsorbing or nonadsorbing flat surfaces, forming a slit geometry. The study is primarily made under "restricted equilibrium" conditions, i.e., below a threshold separation, the chains are allowed to equilibrate conformationally between the surfaces, but they are unable to diffuse into or out from the slit. This is believed to be a reasonable model for commonly encountered experimental situations, when the surfaces are large and adsorbing and the polymers are long. Using a recently presented density functional theory, we are able to compare predictions for chains of finite and infinite length. A major advantage of the infinite chain formulation is that it is a high resolution theory, and predictions from the finite length version will exactly approach the ones for infinite chains, when the degree of polymerization becomes large enough. Our study spans across a relatively large number of relevant system parameters, such as bulk concentration, surface adsorption strength, polymer length, and chain flexibility. The response in terms of the net surface interaction, to a change of a system parameter, is often nonmonotonic. We also make comparisons with predictions it full equilibrium, where the diffusion constraint has been relaxed. We give a specific example of how a diffusion-limited process can lead to hysteresis effects, similar to those observed in many surface force measurements. Finally, in a separate section of this work, we have included some direct experimental comparisons, demonstrating the relevance and applicability of restricted equilibrium conditions to "real world" scenarios. The computational power of the density functional approach is here highlighted, with calculations including semiflexible 20000-mers.},
  author       = {Forsman, Jan and Woodward, Clifford E.},
  issn         = {0024-9297},
  language     = {eng},
  number       = {23},
  pages        = {8396--8408},
  publisher    = {The American Chemical Society},
  series       = {Macromolecules},
  title        = {Surface forces at restricted equilibrium, in solutions containing finite or infinite semiflexible polymers},
  url          = {http://dx.doi.org/10.1021/ma071181t},
  volume       = {40},
  year         = {2007},
}