Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Specific anion effects on the internal structure of a poly (N-isopropylacrylamide) brush

Murdoch, Timothy J ; Humphreys, Ben A LU ; Willott, Joshua D ; Gregory, Kasimir P ; Prescott, Stuart W ; Nelson, Andrew ; Wanless, Erica J and Webber, Grant B (2016) In Macromolecules 49(16). p.6050-6060
Abstract
The effect of anion identity and temperature on the internal nanostructure of poly(N-isopropylacrylamide) brushes were investigated using neutron reflectometry (NR), atomic force microscopy (AFM), and quartz crystal microbalance with dissipation monitoring (QCM-D). NR and QCM-D measurements showed that addition of strongly kosmotropic acetate anions shifted the lower critical solution temperature (LCST) to lower temperatures relative to pure D2O/H2O, while strongly chaotropic thiocyanate anions shifted the LCST to higher temperatures. Polymer density profiles derived from NR showed direct evidence of vertical phase separation at temperatures around the LCST in all conditions. Results indicate that the density... (More)
The effect of anion identity and temperature on the internal nanostructure of poly(N-isopropylacrylamide) brushes were investigated using neutron reflectometry (NR), atomic force microscopy (AFM), and quartz crystal microbalance with dissipation monitoring (QCM-D). NR and QCM-D measurements showed that addition of strongly kosmotropic acetate anions shifted the lower critical solution temperature (LCST) to lower temperatures relative to pure D2O/H2O, while strongly chaotropic thiocyanate anions shifted the LCST to higher temperatures. Polymer density profiles derived from NR showed direct evidence of vertical phase separation at temperatures around the LCST in all conditions. Results indicate that the density profiles were not simple modulations of structures observed in D2O to higher or lower temperatures, with both anion identity and ionic strength found to influence the qualitative features of the profiles. In particular, the presence of thiocyanate broadened the LCST transition which is attributed to the ability of the thiocyanate anion to electrosterically stabilize the brush above its LCST. Complementary AFM data showed that the acetate ion induced collapsed structures while a broader transition is observed in the presence of thiocyanate. (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
49
issue
16
pages
11 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:84983667050
ISSN
0024-9297
DOI
10.1021/acs.macromol.6b01001
language
English
LU publication?
no
id
f91d1915-f310-4998-abdb-cf92bdf06e94
date added to LUP
2022-04-01 21:09:28
date last changed
2022-06-21 04:04:46
@article{f91d1915-f310-4998-abdb-cf92bdf06e94,
  abstract     = {{The effect of anion identity and temperature on the internal nanostructure of poly(<i>N-</i>isopropylacrylamide) brushes were investigated using neutron reflectometry (NR), atomic force microscopy (AFM), and quartz crystal microbalance with dissipation monitoring (QCM-D). NR and QCM-D measurements showed that addition of strongly kosmotropic acetate anions shifted the lower critical solution temperature (LCST) to lower temperatures relative to pure D<sub>2</sub>O/H<sub>2</sub>O, while strongly chaotropic thiocyanate anions shifted the LCST to higher temperatures. Polymer density profiles derived from NR showed direct evidence of vertical phase separation at temperatures around the LCST in all conditions. Results indicate that the density profiles were not simple modulations of structures observed in D<sub>2</sub>O to higher or lower temperatures, with both anion identity and ionic strength found to influence the qualitative features of the profiles. In particular, the presence of thiocyanate broadened the LCST transition which is attributed to the ability of the thiocyanate anion to electrosterically stabilize the brush above its LCST. Complementary AFM data showed that the acetate ion induced collapsed structures while a broader transition is observed in the presence of thiocyanate.}},
  author       = {{Murdoch, Timothy J and Humphreys, Ben A and Willott, Joshua D and Gregory, Kasimir P and Prescott, Stuart W and Nelson, Andrew and Wanless, Erica J and Webber, Grant B}},
  issn         = {{0024-9297}},
  language     = {{eng}},
  number       = {{16}},
  pages        = {{6050--6060}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Macromolecules}},
  title        = {{Specific anion effects on the internal structure of a poly (<i>N</i>-isopropylacrylamide) brush}},
  url          = {{http://dx.doi.org/10.1021/acs.macromol.6b01001}},
  doi          = {{10.1021/acs.macromol.6b01001}},
  volume       = {{49}},
  year         = {{2016}},
}