Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Geometrical Confinement Modulates the Thermoresponse of a Poly (N-isopropylacrylamide) Brush

Gresham, Isaac J. ; Humphreys, Ben A. LU ; Willott, Joshua D. ; Johnson, Edwin C. ; Murdoch, Timothy J. ; Webber, Grant B. ; Wanless, Erica J. ; Nelson, Andrew R. J. and Prescott, Stuart W. (2021) In Macromolecules 54(5). p.2541-2550
Abstract
The structure of grafted-from poly(N-isopropylacrylamide) (PNIPAM) brushes is investigated as a function of confining stress and system temperature using neutron reflectometry (NR), numerical self-consistent field theory, and the reanalysis of colloid probe atomic force microscopy (AFM) data from the literature. For NR experiments, confinement is achieved using a custom-made sample environment, and the corresponding reflectometry data are analyzed using a novel “distribution model.” The NR and AFM experiments probe similar temperature–stress combinations and generally find qualitative agreement, with some variations highlighting path-dependent (isostress vs isothermal, respectively) behavior. All techniques indicate that confinement... (More)
The structure of grafted-from poly(N-isopropylacrylamide) (PNIPAM) brushes is investigated as a function of confining stress and system temperature using neutron reflectometry (NR), numerical self-consistent field theory, and the reanalysis of colloid probe atomic force microscopy (AFM) data from the literature. For NR experiments, confinement is achieved using a custom-made sample environment, and the corresponding reflectometry data are analyzed using a novel “distribution model.” The NR and AFM experiments probe similar temperature–stress combinations and generally find qualitative agreement, with some variations highlighting path-dependent (isostress vs isothermal, respectively) behavior. All techniques indicate that confinement removes the critical transition point in the thermoresponse of PNIPAM and results in the brush assuming a block-like volume fraction profile with a uniform internal structure. The PNIPAM brushes recover from such treatment, regaining their thermoresponse upon resolvation. Understanding the structure of responsive polymer brushes under confinement is essential, as brush applications are often accompanied by a surface-normal force (i.e., lubrication) and brush properties are dependent on their structure. (Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
subject
in
Macromolecules
volume
54
issue
5
pages
10 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85102071739
ISSN
0024-9297
DOI
10.1021/acs.macromol.0c02775
language
English
LU publication?
no
id
00915f7c-ca46-4c8e-ae2b-853101a6823c
date added to LUP
2022-04-01 21:01:48
date last changed
2022-05-10 04:56:53
@article{00915f7c-ca46-4c8e-ae2b-853101a6823c,
  abstract     = {{The structure of grafted-from poly(<i>N</i>-isopropylacrylamide) (PNIPAM) brushes is investigated as a function of confining stress and system temperature using neutron reflectometry (NR), numerical self-consistent field theory, and the reanalysis of colloid probe atomic force microscopy (AFM) data from the literature. For NR experiments, confinement is achieved using a custom-made sample environment, and the corresponding reflectometry data are analyzed using a novel “distribution model.” The NR and AFM experiments probe similar temperature–stress combinations and generally find qualitative agreement, with some variations highlighting path-dependent (isostress vs isothermal, respectively) behavior. All techniques indicate that confinement removes the critical transition point in the thermoresponse of PNIPAM and results in the brush assuming a block-like volume fraction profile with a uniform internal structure. The PNIPAM brushes recover from such treatment, regaining their thermoresponse upon resolvation. Understanding the structure of responsive polymer brushes under confinement is essential, as brush applications are often accompanied by a surface-normal force (i.e., lubrication) and brush properties are dependent on their structure.}},
  author       = {{Gresham, Isaac J. and Humphreys, Ben A. and Willott, Joshua D. and Johnson, Edwin C. and Murdoch, Timothy J. and Webber, Grant B. and Wanless, Erica J. and Nelson, Andrew R. J. and Prescott, Stuart W.}},
  issn         = {{0024-9297}},
  language     = {{eng}},
  number       = {{5}},
  pages        = {{2541--2550}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Macromolecules}},
  title        = {{Geometrical Confinement Modulates the Thermoresponse of a Poly (<i>N</i>-isopropylacrylamide) Brush}},
  url          = {{http://dx.doi.org/10.1021/acs.macromol.0c02775}},
  doi          = {{10.1021/acs.macromol.0c02775}},
  volume       = {{54}},
  year         = {{2021}},
}