Anion-specific effects on the behavior of pH-sensitive polybasic brushes
(2015) In Langmuir 31(12). p.3707-3717- Abstract
- The anion-specific solvation and conformational behavior of weakly basic
poly(2-dimethylamino)ethyl methacrylate (poly(DMA)),
poly(2-diethylamino)ethyl methacrylate (poly(DEA)), and
poly(2-diisopropylamino)ethyl methacrylate (poly(DPA)) brushes, with
correspondingly increasing inherent hydrophobicity, have been
investigated using in situ ellipsometric and quartz crystal
microbalance with dissipation (QCM-D) measurements. In the osmotic brush
regime, as the initial low concentration of salt is increased, the
brushes osmotically swell by the uptake of solvent as they become
charged and the attractive hydrophobic inter- and intrachain
interactions are overcome. With increased ionic... (More) - The anion-specific solvation and conformational behavior of weakly basic
poly(2-dimethylamino)ethyl methacrylate (poly(DMA)),
poly(2-diethylamino)ethyl methacrylate (poly(DEA)), and
poly(2-diisopropylamino)ethyl methacrylate (poly(DPA)) brushes, with
correspondingly increasing inherent hydrophobicity, have been
investigated using in situ ellipsometric and quartz crystal
microbalance with dissipation (QCM-D) measurements. In the osmotic brush
regime, as the initial low concentration of salt is increased, the
brushes osmotically swell by the uptake of solvent as they become
charged and the attractive hydrophobic inter- and intrachain
interactions are overcome. With increased ionic strength, the brushes
move into the salted brush regime where they desolvate and collapse as
their electrostatic charge is screened. Here, as the brushes collapse,
they transition to more uniform and rigid conformations, which dissipate
less energy, than similarly solvated brushes at lower ionic strength.
Significantly, in these distinct regimes brush behavior is not only
ionic strength dependent but is also influenced by the nature of the
added salt based on its position in the well-known Hofmeister or
lyotropic series, with potassium acetate, nitrate, and thiocyanate
investigated. The strongly kosmotropic acetate anions display low
affinity for the hydrophobic polymers, and largely unscreened
electrosteric repulsions allow the brushes to remain highly solvated at
higher acetate concentrations. The mildly chaotropic nitrate and
strongly chaotropic thiocyanate anions exhibit a polymer
hydrophobicity-dependent affinity for the brushes. Increasing
thiocyanate concentration causes the brushes to collapse at lower ionic
strength than for the other two anions. This study of weak polybasic
brushes demonstrates the importance of all ion, solvent, and polymer
interactions. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/af1b5e23-eeb8-4b11-8f1b-e8149af5c1cd
- author
- Willott, Joshua D ; Murdoch, Timothy J ; Humphreys, Ben A LU ; Edmondson, Steve ; Wanless, Erica J and Webber, Grant B
- publishing date
- 2015
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Langmuir
- volume
- 31
- issue
- 12
- pages
- 11 pages
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- scopus:84925989906
- ISSN
- 0743-7463
- DOI
- 10.1021/acs.langmuir.5b00116
- language
- English
- LU publication?
- no
- id
- af1b5e23-eeb8-4b11-8f1b-e8149af5c1cd
- date added to LUP
- 2022-04-01 21:10:39
- date last changed
- 2022-04-25 19:35:01
@article{af1b5e23-eeb8-4b11-8f1b-e8149af5c1cd,
abstract = {{The anion-specific solvation and conformational behavior of weakly basic<br>
poly(2-dimethylamino)ethyl methacrylate (poly(DMA)), <br>
poly(2-diethylamino)ethyl methacrylate (poly(DEA)), and <br>
poly(2-diisopropylamino)ethyl methacrylate (poly(DPA)) brushes, with <br>
correspondingly increasing inherent hydrophobicity, have been <br>
investigated using <i>in situ</i> ellipsometric and quartz crystal <br>
microbalance with dissipation (QCM-D) measurements. In the osmotic brush<br>
regime, as the initial low concentration of salt is increased, the <br>
brushes osmotically swell by the uptake of solvent as they become <br>
charged and the attractive hydrophobic inter- and intrachain <br>
interactions are overcome. With increased ionic strength, the brushes <br>
move into the salted brush regime where they desolvate and collapse as <br>
their electrostatic charge is screened. Here, as the brushes collapse, <br>
they transition to more uniform and rigid conformations, which dissipate<br>
less energy, than similarly solvated brushes at lower ionic strength. <br>
Significantly, in these distinct regimes brush behavior is not only <br>
ionic strength dependent but is also influenced by the nature of the <br>
added salt based on its position in the well-known Hofmeister or <br>
lyotropic series, with potassium acetate, nitrate, and thiocyanate <br>
investigated. The strongly kosmotropic acetate anions display low <br>
affinity for the hydrophobic polymers, and largely unscreened <br>
electrosteric repulsions allow the brushes to remain highly solvated at <br>
higher acetate concentrations. The mildly chaotropic nitrate and <br>
strongly chaotropic thiocyanate anions exhibit a polymer <br>
hydrophobicity-dependent affinity for the brushes. Increasing <br>
thiocyanate concentration causes the brushes to collapse at lower ionic <br>
strength than for the other two anions. This study of weak polybasic <br>
brushes demonstrates the importance of all ion, solvent, and polymer <br>
interactions.}},
author = {{Willott, Joshua D and Murdoch, Timothy J and Humphreys, Ben A and Edmondson, Steve and Wanless, Erica J and Webber, Grant B}},
issn = {{0743-7463}},
language = {{eng}},
number = {{12}},
pages = {{3707--3717}},
publisher = {{The American Chemical Society (ACS)}},
series = {{Langmuir}},
title = {{Anion-specific effects on the behavior of pH-sensitive polybasic brushes}},
url = {{http://dx.doi.org/10.1021/acs.langmuir.5b00116}},
doi = {{10.1021/acs.langmuir.5b00116}},
volume = {{31}},
year = {{2015}},
}