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Surface Adsorption and Phase Separation of Oppositely Charged Polyion-Surfactant Ion Complexes: 3. Effects of Polyion Hydrophobicity.

Santos, Olga LU ; Johnson, Eric S; Nylander, Tommy LU ; Panandiker, Rajan K; Sivik, Mark R and Piculell, Lennart LU (2010) In Langmuir 26(12). p.9357-9367
Abstract
The adsorption to hydrophilic silica surfaces in relation to the bulk phase behavior was investigated by in situ null ellipsometry and bulk turbidity measurements for four cationic copolymers of varying hydrophobicity in mixtures with anionic surfactant sodium dodecylsulfate (SDS). The purpose was to reveal the effect of polyion hydrophobicity on the association with surfactant at surfaces and in the bulk. All polyelectrolytes contained 20 wt % cationic units and had similar molecular weights. An increase in surfactant concentration by the stepwise addition of SDS to a dilute polyelectrolyte solution led to an increase in both the adsorbed amount and bulk turbidity, starting at a defined SDS concentration, as a result of the formation of... (More)
The adsorption to hydrophilic silica surfaces in relation to the bulk phase behavior was investigated by in situ null ellipsometry and bulk turbidity measurements for four cationic copolymers of varying hydrophobicity in mixtures with anionic surfactant sodium dodecylsulfate (SDS). The purpose was to reveal the effect of polyion hydrophobicity on the association with surfactant at surfaces and in the bulk. All polyelectrolytes contained 20 wt % cationic units and had similar molecular weights. An increase in surfactant concentration by the stepwise addition of SDS to a dilute polyelectrolyte solution led to an increase in both the adsorbed amount and bulk turbidity, starting at a defined SDS concentration, as a result of the formation of insoluble polyion-surfactant ion complexes. At some higher SDS concentration, the formed aggregates started to redissolve gradually in the bulk and desorb from the surface because of the overcharging of the complexes. The SDS concentration at which the maxima in adsorption and turbidity occurred increased with decreasing polyion hydrophobicity; the more hydrophobic polyions bound excess SDS more readily, and the aggregates therefore redissolved at a lower SDS concentration. The adsorption from polyelectrolyte-SDS solutions, premixed at SDS concentrations above the adsorption maximum, which occurred on diluting the solution by "rinsing" the ellipsometer cuvette with 1 mM NaCl, was also investigated. On dilution, both the turbidity and the adsorbed amount increased as the excess surfactant in the polyion-surfactant ion complexes progressively decreased. More efficient deposition was achieved if the initial SDS concentration was close to the adsorption maximum. The latter situation could be achieved either by adjusting the SDS concentration or, at a fixed SDS concentration, by choosing a polyion with the appropriate hydrophobicity. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Langmuir
volume
26
issue
12
pages
9357 - 9367
publisher
The American Chemical Society
external identifiers
  • wos:000278427600030
  • pmid:20334408
  • scopus:78651344005
ISSN
0743-7463
DOI
10.1021/la1003353
language
English
LU publication?
yes
id
16c0f149-6b02-48b4-9212-f64440925ff1 (old id 1581737)
date added to LUP
2010-04-29 17:04:11
date last changed
2018-05-29 11:48:04
@article{16c0f149-6b02-48b4-9212-f64440925ff1,
  abstract     = {The adsorption to hydrophilic silica surfaces in relation to the bulk phase behavior was investigated by in situ null ellipsometry and bulk turbidity measurements for four cationic copolymers of varying hydrophobicity in mixtures with anionic surfactant sodium dodecylsulfate (SDS). The purpose was to reveal the effect of polyion hydrophobicity on the association with surfactant at surfaces and in the bulk. All polyelectrolytes contained 20 wt % cationic units and had similar molecular weights. An increase in surfactant concentration by the stepwise addition of SDS to a dilute polyelectrolyte solution led to an increase in both the adsorbed amount and bulk turbidity, starting at a defined SDS concentration, as a result of the formation of insoluble polyion-surfactant ion complexes. At some higher SDS concentration, the formed aggregates started to redissolve gradually in the bulk and desorb from the surface because of the overcharging of the complexes. The SDS concentration at which the maxima in adsorption and turbidity occurred increased with decreasing polyion hydrophobicity; the more hydrophobic polyions bound excess SDS more readily, and the aggregates therefore redissolved at a lower SDS concentration. The adsorption from polyelectrolyte-SDS solutions, premixed at SDS concentrations above the adsorption maximum, which occurred on diluting the solution by "rinsing" the ellipsometer cuvette with 1 mM NaCl, was also investigated. On dilution, both the turbidity and the adsorbed amount increased as the excess surfactant in the polyion-surfactant ion complexes progressively decreased. More efficient deposition was achieved if the initial SDS concentration was close to the adsorption maximum. The latter situation could be achieved either by adjusting the SDS concentration or, at a fixed SDS concentration, by choosing a polyion with the appropriate hydrophobicity.},
  author       = {Santos, Olga and Johnson, Eric  S and Nylander, Tommy and Panandiker, Rajan K and Sivik, Mark R and Piculell, Lennart},
  issn         = {0743-7463},
  language     = {eng},
  number       = {12},
  pages        = {9357--9367},
  publisher    = {The American Chemical Society},
  series       = {Langmuir},
  title        = {Surface Adsorption and Phase Separation of Oppositely Charged Polyion-Surfactant Ion Complexes: 3. Effects of Polyion Hydrophobicity.},
  url          = {http://dx.doi.org/10.1021/la1003353},
  volume       = {26},
  year         = {2010},
}