Combined Experimental and Theoretical Study of Weak Polyelectrolyte Brushes in Salt Mixtures

Joshua D. Willott (Corresponding Author), Ben A. Humphreys, Grant B. Webber, Erica J. Wanless, Wiebe M. De Vos

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)
12 Downloads (Pure)

Abstract

The swelling behavior of a hydrophobic poly(2diisopropylamino)ethyl methacrylate (PDPA) brush immersed in aqueous solutions of single and mixed salts has been investigated using ellipsometry and numerical self-consistent field (nSCF) theory. As a function of solution ionic strength, the osmotic and salted brush regimes of weak polyelectrolyte brushes as well as substantial specific anion effects in the presence of K + salts of Cl - , NO 3 - , and SCN - are found. For solutions containing mixtures of NO 3 - and Cl - , the brush swelling is the same as one would expect on the basis of the concentration-weighted average of the brush behavior in the single salt solutions. However, in mixtures of SCN - and Cl - , the swelling response is more complicated and substantial divergence from ideal behavior is observed. Mean-field theory shows excellent qualitative agreement with the ellipsometry findings. nSCF reveals that for the SCN - /Cl - cases the swelling behavior of the PDPA brush most likely arises from the predominant localization of the weakly hydrated SCN - within the brush compared to the more strongly hydrated Cl - .

Original languageEnglish
Pages (from-to)2709-2718
Number of pages10
JournalLangmuir
Volume35
Issue number7
DOIs
Publication statusPublished - 19 Feb 2019

Fingerprint

brushes
Brushes
Polyelectrolytes
Salts
salts
swelling
Swelling
Ellipsometry
ellipsometry
self consistent fields
Mean field theory
Ionic strength
Anions
divergence
Negative ions
anions
aqueous solutions

Cite this

Willott, Joshua D. ; Humphreys, Ben A. ; Webber, Grant B. ; Wanless, Erica J. ; De Vos, Wiebe M. / Combined Experimental and Theoretical Study of Weak Polyelectrolyte Brushes in Salt Mixtures. In: Langmuir. 2019 ; Vol. 35, No. 7. pp. 2709-2718.
@article{f0192b35fa0148e1b2d005087f9eaa40,
title = "Combined Experimental and Theoretical Study of Weak Polyelectrolyte Brushes in Salt Mixtures",
abstract = "The swelling behavior of a hydrophobic poly(2diisopropylamino)ethyl methacrylate (PDPA) brush immersed in aqueous solutions of single and mixed salts has been investigated using ellipsometry and numerical self-consistent field (nSCF) theory. As a function of solution ionic strength, the osmotic and salted brush regimes of weak polyelectrolyte brushes as well as substantial specific anion effects in the presence of K + salts of Cl - , NO 3 - , and SCN - are found. For solutions containing mixtures of NO 3 - and Cl - , the brush swelling is the same as one would expect on the basis of the concentration-weighted average of the brush behavior in the single salt solutions. However, in mixtures of SCN - and Cl - , the swelling response is more complicated and substantial divergence from ideal behavior is observed. Mean-field theory shows excellent qualitative agreement with the ellipsometry findings. nSCF reveals that for the SCN - /Cl - cases the swelling behavior of the PDPA brush most likely arises from the predominant localization of the weakly hydrated SCN - within the brush compared to the more strongly hydrated Cl - .",
author = "Willott, {Joshua D.} and Humphreys, {Ben A.} and Webber, {Grant B.} and Wanless, {Erica J.} and {De Vos}, {Wiebe M.}",
year = "2019",
month = "2",
day = "19",
doi = "10.1021/acs.langmuir.8b03838",
language = "English",
volume = "35",
pages = "2709--2718",
journal = "Langmuir",
issn = "0743-7463",
publisher = "American Chemical Society",
number = "7",

}

Combined Experimental and Theoretical Study of Weak Polyelectrolyte Brushes in Salt Mixtures. / Willott, Joshua D. (Corresponding Author); Humphreys, Ben A.; Webber, Grant B.; Wanless, Erica J.; De Vos, Wiebe M.

In: Langmuir, Vol. 35, No. 7, 19.02.2019, p. 2709-2718.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Combined Experimental and Theoretical Study of Weak Polyelectrolyte Brushes in Salt Mixtures

AU - Willott, Joshua D.

AU - Humphreys, Ben A.

AU - Webber, Grant B.

AU - Wanless, Erica J.

AU - De Vos, Wiebe M.

PY - 2019/2/19

Y1 - 2019/2/19

N2 - The swelling behavior of a hydrophobic poly(2diisopropylamino)ethyl methacrylate (PDPA) brush immersed in aqueous solutions of single and mixed salts has been investigated using ellipsometry and numerical self-consistent field (nSCF) theory. As a function of solution ionic strength, the osmotic and salted brush regimes of weak polyelectrolyte brushes as well as substantial specific anion effects in the presence of K + salts of Cl - , NO 3 - , and SCN - are found. For solutions containing mixtures of NO 3 - and Cl - , the brush swelling is the same as one would expect on the basis of the concentration-weighted average of the brush behavior in the single salt solutions. However, in mixtures of SCN - and Cl - , the swelling response is more complicated and substantial divergence from ideal behavior is observed. Mean-field theory shows excellent qualitative agreement with the ellipsometry findings. nSCF reveals that for the SCN - /Cl - cases the swelling behavior of the PDPA brush most likely arises from the predominant localization of the weakly hydrated SCN - within the brush compared to the more strongly hydrated Cl - .

AB - The swelling behavior of a hydrophobic poly(2diisopropylamino)ethyl methacrylate (PDPA) brush immersed in aqueous solutions of single and mixed salts has been investigated using ellipsometry and numerical self-consistent field (nSCF) theory. As a function of solution ionic strength, the osmotic and salted brush regimes of weak polyelectrolyte brushes as well as substantial specific anion effects in the presence of K + salts of Cl - , NO 3 - , and SCN - are found. For solutions containing mixtures of NO 3 - and Cl - , the brush swelling is the same as one would expect on the basis of the concentration-weighted average of the brush behavior in the single salt solutions. However, in mixtures of SCN - and Cl - , the swelling response is more complicated and substantial divergence from ideal behavior is observed. Mean-field theory shows excellent qualitative agreement with the ellipsometry findings. nSCF reveals that for the SCN - /Cl - cases the swelling behavior of the PDPA brush most likely arises from the predominant localization of the weakly hydrated SCN - within the brush compared to the more strongly hydrated Cl - .

UR - http://www.scopus.com/inward/record.url?scp=85061556335&partnerID=8YFLogxK

U2 - 10.1021/acs.langmuir.8b03838

DO - 10.1021/acs.langmuir.8b03838

M3 - Article

VL - 35

SP - 2709

EP - 2718

JO - Langmuir

JF - Langmuir

SN - 0743-7463

IS - 7

ER -