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Rheology of mixed solutions of an associating polymer with a surfactant. Why are different surfactants different?

Piculell, Lennart LU ; Egermayer, Monica LU and Sjöström, Jesper LU (2003) In Langmuir 19(9). p.3643-3649
Abstract
The effects of nine different anionic and cationic micelle-forming surfactants on the viscosity and viscoelasticity of semidilute solutions of hydrophobically modified hydroxyethyl cellulose (HMHEC) were studied. All added surfactants gave rise to the well-established viscosity maximum with increasing surfactant concentration, but the total surfactant concentration at the maximum, as well as the magnitude of the viscosity enhancement, varied wide

y between the different surfactants. A detailed analysis of the oscillatory shear data for the most viscous samples showed that added surfactant affects both the lifetime and the structure of the transient HMHEC-surfactant network, due to mixed micellization between surfactant molecules... (More)
The effects of nine different anionic and cationic micelle-forming surfactants on the viscosity and viscoelasticity of semidilute solutions of hydrophobically modified hydroxyethyl cellulose (HMHEC) were studied. All added surfactants gave rise to the well-established viscosity maximum with increasing surfactant concentration, but the total surfactant concentration at the maximum, as well as the magnitude of the viscosity enhancement, varied wide

y between the different surfactants. A detailed analysis of the oscillatory shear data for the most viscous samples showed that added surfactant affects both the lifetime and the structure of the transient HMHEC-surfactant network, due to mixed micellization between surfactant molecules and the hydrophobic side chains of HMHEC. The viscosity maximum is the result of two opposing effects of increasing surfactant concentration: an increase in the lifetime of mixed micellar cross-links and a decrease in the number of cross-links. All data indicate that the structure of the HMHEC-surfactant network and the compositions of the mixed micellar cross-links are quite similar for the various surfactants, when the mixtures are compared at their respective viscosity maxima. The shifts of the viscosity versus surfactant concentration curves between the various surfactants may thus be rationalized in terms of differences in lifetimes of the mixed micellar junctions and in the proportions of free (monomeric) surfactant. T

e free surfactant concentration at a given degree of surfactant binding is proportional to the critical micelle concentration of the surfactant. The lifetime of a mixed micellar cross-link increases with surfactant chain length and with the nature of the hydrophilic headgroup according to the series trimethylammonium < ammonium approximate to diethoxysulfate < sulfate. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Langmuir
volume
19
issue
9
pages
3643 - 3649
publisher
The American Chemical Society
external identifiers
  • wos:000182467100013
  • scopus:0038680694
ISSN
0743-7463
DOI
10.1021/la020912+
language
English
LU publication?
yes
id
9f29e10f-afd0-476c-a3da-0d37f6fb734e (old id 122152)
date added to LUP
2007-07-12 09:47:57
date last changed
2018-01-07 06:10:25
@article{9f29e10f-afd0-476c-a3da-0d37f6fb734e,
  abstract     = {The effects of nine different anionic and cationic micelle-forming surfactants on the viscosity and viscoelasticity of semidilute solutions of hydrophobically modified hydroxyethyl cellulose (HMHEC) were studied. All added surfactants gave rise to the well-established viscosity maximum with increasing surfactant concentration, but the total surfactant concentration at the maximum, as well as the magnitude of the viscosity enhancement, varied wide<br/><br>
y between the different surfactants. A detailed analysis of the oscillatory shear data for the most viscous samples showed that added surfactant affects both the lifetime and the structure of the transient HMHEC-surfactant network, due to mixed micellization between surfactant molecules and the hydrophobic side chains of HMHEC. The viscosity maximum is the result of two opposing effects of increasing surfactant concentration: an increase in the lifetime of mixed micellar cross-links and a decrease in the number of cross-links. All data indicate that the structure of the HMHEC-surfactant network and the compositions of the mixed micellar cross-links are quite similar for the various surfactants, when the mixtures are compared at their respective viscosity maxima. The shifts of the viscosity versus surfactant concentration curves between the various surfactants may thus be rationalized in terms of differences in lifetimes of the mixed micellar junctions and in the proportions of free (monomeric) surfactant. T<br/><br>
e free surfactant concentration at a given degree of surfactant binding is proportional to the critical micelle concentration of the surfactant. The lifetime of a mixed micellar cross-link increases with surfactant chain length and with the nature of the hydrophilic headgroup according to the series trimethylammonium &lt; ammonium approximate to diethoxysulfate &lt; sulfate.},
  author       = {Piculell, Lennart and Egermayer, Monica and Sjöström, Jesper},
  issn         = {0743-7463},
  language     = {eng},
  number       = {9},
  pages        = {3643--3649},
  publisher    = {The American Chemical Society},
  series       = {Langmuir},
  title        = {Rheology of mixed solutions of an associating polymer with a surfactant. Why are different surfactants different?},
  url          = {http://dx.doi.org/10.1021/la020912+},
  volume       = {19},
  year         = {2003},
}