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Molecular self-diffusion in micellar and discrete cubic phases of an ionic surfactant with mixed monovalent/polymeric counterions

Svensson, Anna LU ; Topgaard, Daniel LU ; Piculell, Lennart LU and Söderman, Olle LU (2003) In The Journal of Physical Chemistry Part B 107(47). p.13241-13250
Abstract
The molecular self-diffusion in concentrated aqueous mixtures based on an oppositely charged po

ymer-surfactant pair has been investigated by NMR pulsed field gradient techniques. The investigated structures were an ordered cubic Pm3n phase (ca. 50 wt % water) and a disordered micellar phase, both containing cetyltrimethylammonium (CTA(+)) micelles with mixed acetate (Ac-) and polyacrylate (PA(-)) counterions. In the cubic phase, CTA(+) gave broad lines in the H-1 NMR spectrum, which made it possible to use the pulsed field gradient (PFG) spin echo (SE) technique to measure the PA(-) diffusion. The observed diffusion coefficients for the four different molecular species covered 4 orders of magnitude with the rate of diffusion... (More)
The molecular self-diffusion in concentrated aqueous mixtures based on an oppositely charged po

ymer-surfactant pair has been investigated by NMR pulsed field gradient techniques. The investigated structures were an ordered cubic Pm3n phase (ca. 50 wt % water) and a disordered micellar phase, both containing cetyltrimethylammonium (CTA(+)) micelles with mixed acetate (Ac-) and polyacrylate (PA(-)) counterions. In the cubic phase, CTA(+) gave broad lines in the H-1 NMR spectrum, which made it possible to use the pulsed field gradient (PFG) spin echo (SE) technique to measure the PA(-) diffusion. The observed diffusion coefficients for the four different molecular species covered 4 orders of magnitude with the rate of diffusion decreasing in the order water > Ac- > PA(-) > CTA(+). For all species, the diffusion coefficients were largely insensitive to the counterion composition. A model considering obstruction effects and binding to the micelles could account for the reduced diffusion of Ac- and CTA(+) compared to dilute reference solutions. For water, the reduction of the diffusion was mainly

ue to obstruction effects. The PA(-) diffusion was much more retarded than the

Ac- diffusion in the cubic phase; moreover, the molecular weight

dependence of the diffusion was dramatically enhanced for the

polydisperse polyion. Both effects are attributed to electrostatic

attractions and obstruction effects experienced by polyions diffusing

in a concentrated matrix of stationary

micelles. (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
The Journal of Physical Chemistry Part B
volume
107
issue
47
pages
13241 - 13250
publisher
The American Chemical Society
external identifiers
  • wos:000186762200045
  • scopus:0344272197
ISSN
1520-5207
DOI
10.1021/jp0348225
language
English
LU publication?
yes
id
7c6f4eb1-aff1-4224-a905-db43d552810c (old id 122236)
date added to LUP
2007-07-12 12:11:04
date last changed
2018-01-07 08:34:37
@article{7c6f4eb1-aff1-4224-a905-db43d552810c,
  abstract     = {The molecular self-diffusion in concentrated aqueous mixtures based on an oppositely charged po<br/><br>
ymer-surfactant pair has been investigated by NMR pulsed field gradient techniques. The investigated structures were an ordered cubic Pm3n phase (ca. 50 wt % water) and a disordered micellar phase, both containing cetyltrimethylammonium (CTA(+)) micelles with mixed acetate (Ac-) and polyacrylate (PA(-)) counterions. In the cubic phase, CTA(+) gave broad lines in the H-1 NMR spectrum, which made it possible to use the pulsed field gradient (PFG) spin echo (SE) technique to measure the PA(-) diffusion. The observed diffusion coefficients for the four different molecular species covered 4 orders of magnitude with the rate of diffusion decreasing in the order water &gt; Ac- &gt; PA(-) &gt; CTA(+). For all species, the diffusion coefficients were largely insensitive to the counterion composition. A model considering obstruction effects and binding to the micelles could account for the reduced diffusion of Ac- and CTA(+) compared to dilute reference solutions. For water, the reduction of the diffusion was mainly <br/><br>
ue to obstruction effects. The PA(-) diffusion was much more retarded than the<br/><br>
	Ac- diffusion in the cubic phase; moreover, the molecular weight<br/><br>
	dependence of the diffusion was dramatically enhanced for the<br/><br>
	polydisperse polyion. Both effects are attributed to electrostatic<br/><br>
	attractions and obstruction effects experienced by polyions diffusing<br/><br>
	in a concentrated matrix of stationary<br/><br>
	micelles.},
  author       = {Svensson, Anna and Topgaard, Daniel and Piculell, Lennart and Söderman, Olle},
  issn         = {1520-5207},
  language     = {eng},
  number       = {47},
  pages        = {13241--13250},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Molecular self-diffusion in micellar and discrete cubic phases of an ionic surfactant with mixed monovalent/polymeric counterions},
  url          = {http://dx.doi.org/10.1021/jp0348225},
  volume       = {107},
  year         = {2003},
}