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Novel evaluation method of neutron reflectivity data applied to stimulus-responsive polymer brushes

Zhang, Jianming; Nylander, Tommy LU ; Campbell, Richard LU ; Rennie, Adrian R; Zauscher, Stefan and Linse, Per LU (2008) In Soft Matter 4(3). p.500-509
Abstract
Neutron reflectivity (NR) measurements have been performed on stimulus-responsive polymer brushes containing N-isopropylacrylamide (NIPAAM) at different temperatures and contrasts using two different brush samples of roughly the same grafting density and layer thickness. The NR data were analyzed using a novel method employing polymer density profiles predicted from lattice mean-field theory augmented with a polymer model to describe polymer solubility that decreases with increasing temperature. The predicted density profiles at the different temperatures were self-consistent with the experimentally observed profiles; hence the experimental data lend credibility to the theory. We found that the brush thickness decreased from 220 to 160 nm... (More)
Neutron reflectivity (NR) measurements have been performed on stimulus-responsive polymer brushes containing N-isopropylacrylamide (NIPAAM) at different temperatures and contrasts using two different brush samples of roughly the same grafting density and layer thickness. The NR data were analyzed using a novel method employing polymer density profiles predicted from lattice mean-field theory augmented with a polymer model to describe polymer solubility that decreases with increasing temperature. The predicted density profiles at the different temperatures were self-consistent with the experimentally observed profiles; hence the experimental data lend credibility to the theory. We found that the brush thickness decreased from 220 to 160 nm and the polymer volume fraction increased from 55 to 75% when increasing temperature from 293 to 328 K. The new evaluation approach involved significantly fewer independent fitting parameters than methods involving layers of uniform densities. Furthermore, the approach can straightforwardly be extended to analyze neutron reflectivity data of grafted, weakly charged polymers that display pH-sensitive behaviour and also to block copolymers and to surfaces with adsorbed polymers. We propose that such accurate model calculations provide a tool to interpret results from NR experiments more effectively and design neutron reflectivity experiments for optimal outcome. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Soft Matter
volume
4
issue
3
pages
500 - 509
publisher
Royal Society of Chemistry
external identifiers
  • wos:000253492400016
  • scopus:39749129626
ISSN
1744-6848
DOI
10.1039/b714911e
language
English
LU publication?
yes
id
2a1c977e-dd7b-4687-b4ca-139122808db8 (old id 1193713)
date added to LUP
2008-09-09 09:51:49
date last changed
2017-02-26 03:57:32
@article{2a1c977e-dd7b-4687-b4ca-139122808db8,
  abstract     = {Neutron reflectivity (NR) measurements have been performed on stimulus-responsive polymer brushes containing N-isopropylacrylamide (NIPAAM) at different temperatures and contrasts using two different brush samples of roughly the same grafting density and layer thickness. The NR data were analyzed using a novel method employing polymer density profiles predicted from lattice mean-field theory augmented with a polymer model to describe polymer solubility that decreases with increasing temperature. The predicted density profiles at the different temperatures were self-consistent with the experimentally observed profiles; hence the experimental data lend credibility to the theory. We found that the brush thickness decreased from 220 to 160 nm and the polymer volume fraction increased from 55 to 75% when increasing temperature from 293 to 328 K. The new evaluation approach involved significantly fewer independent fitting parameters than methods involving layers of uniform densities. Furthermore, the approach can straightforwardly be extended to analyze neutron reflectivity data of grafted, weakly charged polymers that display pH-sensitive behaviour and also to block copolymers and to surfaces with adsorbed polymers. We propose that such accurate model calculations provide a tool to interpret results from NR experiments more effectively and design neutron reflectivity experiments for optimal outcome.},
  author       = {Zhang, Jianming and Nylander, Tommy and Campbell, Richard and Rennie, Adrian R and Zauscher, Stefan and Linse, Per},
  issn         = {1744-6848},
  language     = {eng},
  number       = {3},
  pages        = {500--509},
  publisher    = {Royal Society of Chemistry},
  series       = {Soft Matter},
  title        = {Novel evaluation method of neutron reflectivity data applied to stimulus-responsive polymer brushes},
  url          = {http://dx.doi.org/10.1039/b714911e},
  volume       = {4},
  year         = {2008},
}