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Investigation of a 31% Charged Cationic Polyelectrolyte Interacting with Sodium Dodecylsulfate in Bulk Solution and as a Preadsorbed Layer on Mica. Low Ionic Strength

Fielden, Matthew L.; Claesson, Per M. and Schillén, Karin LU (1998) In Langmuir 14(19). p.5366-5375
Abstract
The behavior of mixtures of a cationic polyelectrolyte of intermediate charge density (31%) and anionic surfactant both in bulk and at a negatively charged solid surface has been investigated. The polyelectrolyte employed was a random copolymer of the neutral acrylamide and cationic [3-(2-methylpropionamido)propyl]trimethylammonium chloride, and the surfactant was sodium dodecyl sulfate (SDS). Measurements of flocculation and electrophoretic mobility in bulk solution clearly showed a phase separation with a maximum in turbidity corresponding roughly to charge neutralization of the polyelectrolyte/surfactant complex. Conductivity measured at low SDS concentrations showed a strong uptake of ions by the polyelectrolyte at a critical SDS... (More)
The behavior of mixtures of a cationic polyelectrolyte of intermediate charge density (31%) and anionic surfactant both in bulk and at a negatively charged solid surface has been investigated. The polyelectrolyte employed was a random copolymer of the neutral acrylamide and cationic [3-(2-methylpropionamido)propyl]trimethylammonium chloride, and the surfactant was sodium dodecyl sulfate (SDS). Measurements of flocculation and electrophoretic mobility in bulk solution clearly showed a phase separation with a maximum in turbidity corresponding roughly to charge neutralization of the polyelectrolyte/surfactant complex. Conductivity measured at low SDS concentrations showed a strong uptake of ions by the polyelectrolyte at a critical SDS concentration. The interferometric surface force apparatus was used to measure forces between muscovite mica surfaces onto which the polyelectrolyte was adsorbed from a 20 ppm, 10-4 M KBr solution. After the polymer solution was replaced with polymer-free 10-4 M KBr solution, a weak long range double-layer repulsion was observed between approaching surfaces, with a bridging attraction dominating at smaller separations. A weak adhesion was observed upon separating the surfaces. Addition of 4.2 × 10-4 M SDS caused a large swelling of the preadsorbed polymer layer due to formation of an associative complex between the polymer and surfactant. Further increasing the SDS concentration decreased the force and layer thickness due to screening of the electrostatic repulsion within the layers and some desorption of polymer molecules. That a slight desorption did occur was supported by electron spectroscopy for chemical analysis measurements. The results broaden the understanding of the effect of polyelectrolyte charge density on the interaction of preadsorbed polyelectrolyte layers with oppositely charged surfactants. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Langmuir
volume
14
issue
19
pages
5366 - 5375
publisher
The American Chemical Society
ISSN
0743-7463
DOI
10.1021/la980456i
language
English
LU publication?
yes
id
597133b1-a5e6-4052-946a-ede79fc180f8 (old id 1736922)
date added to LUP
2010-12-14 16:26:02
date last changed
2016-04-15 19:35:18
@article{597133b1-a5e6-4052-946a-ede79fc180f8,
  abstract     = {The behavior of mixtures of a cationic polyelectrolyte of intermediate charge density (31%) and anionic surfactant both in bulk and at a negatively charged solid surface has been investigated. The polyelectrolyte employed was a random copolymer of the neutral acrylamide and cationic [3-(2-methylpropionamido)propyl]trimethylammonium chloride, and the surfactant was sodium dodecyl sulfate (SDS). Measurements of flocculation and electrophoretic mobility in bulk solution clearly showed a phase separation with a maximum in turbidity corresponding roughly to charge neutralization of the polyelectrolyte/surfactant complex. Conductivity measured at low SDS concentrations showed a strong uptake of ions by the polyelectrolyte at a critical SDS concentration. The interferometric surface force apparatus was used to measure forces between muscovite mica surfaces onto which the polyelectrolyte was adsorbed from a 20 ppm, 10-4 M KBr solution. After the polymer solution was replaced with polymer-free 10-4 M KBr solution, a weak long range double-layer repulsion was observed between approaching surfaces, with a bridging attraction dominating at smaller separations. A weak adhesion was observed upon separating the surfaces. Addition of 4.2 × 10-4 M SDS caused a large swelling of the preadsorbed polymer layer due to formation of an associative complex between the polymer and surfactant. Further increasing the SDS concentration decreased the force and layer thickness due to screening of the electrostatic repulsion within the layers and some desorption of polymer molecules. That a slight desorption did occur was supported by electron spectroscopy for chemical analysis measurements. The results broaden the understanding of the effect of polyelectrolyte charge density on the interaction of preadsorbed polyelectrolyte layers with oppositely charged surfactants.},
  author       = {Fielden, Matthew L. and Claesson, Per M. and Schillén, Karin},
  issn         = {0743-7463},
  language     = {eng},
  number       = {19},
  pages        = {5366--5375},
  publisher    = {The American Chemical Society},
  series       = {Langmuir},
  title        = {Investigation of a 31% Charged Cationic Polyelectrolyte Interacting with Sodium Dodecylsulfate in Bulk Solution and as a Preadsorbed Layer on Mica. Low Ionic Strength},
  url          = {http://dx.doi.org/10.1021/la980456i},
  volume       = {14},
  year         = {1998},
}