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Effects of an amphiphilic graft copolymer on an oil-continuous microemulsion. Molecular self-diffusion and viscosity

Holmberg, A; Piculell, Lennart LU and Nyden, M (2002) In The Journal of Physical Chemistry Part B 106(10). p.2533-2544
Abstract
Mixtures of an amphiphilic graft copolymer in water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/cyclohexane oil-continuous microemulsions are studied by the PGSE NMR technique and by viscometry. The graft copolymer has an oil-soluble poly(dodecyl methacrylate) backbone and water-soluble poly(ethylene glycol) side chains. Water, surfactant, and polymer self-diffusion coefficients can be measured individually by PGSE NMR. The water and the surfactant self-diffusion coefficients are equal, and both monitor the overall diffusion of the water droplets of the microemulsion. The graft copolymer enhances the microemulsion viscosity (relative increase = 2000), and large viscosifying effects are promoted by increased degrees of grafting, increased... (More)
Mixtures of an amphiphilic graft copolymer in water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/cyclohexane oil-continuous microemulsions are studied by the PGSE NMR technique and by viscometry. The graft copolymer has an oil-soluble poly(dodecyl methacrylate) backbone and water-soluble poly(ethylene glycol) side chains. Water, surfactant, and polymer self-diffusion coefficients can be measured individually by PGSE NMR. The water and the surfactant self-diffusion coefficients are equal, and both monitor the overall diffusion of the water droplets of the microemulsion. The graft copolymer enhances the microemulsion viscosity (relative increase = 2000), and large viscosifying effects are promoted by increased degrees of grafting, increased polymer concentration, and large water droplets. Systems with high viscosities always display slow polymer self-diffusion. The droplet diffusion is always much more rapid than the polymer diffusion; thus, the polymer molecules do not immobilize the droplets. The results give the following microscopic picture of the mixtures. Polydisperse, but mostly finite, polymer-droplet aggregates coexist with a large fraction (30%) of "free" droplets. The aggregate size varies strongly with the polymer concentration, but only at the highest polymer concentration investigated (28 g/dm(3)) is there evidence of a fraction of very large (possibly infinite) aggregates. If the polymer/droplet ratio is increased, or if the mixture is diluted by oil, the system responds by inserting more polymer side chains per bound droplet, thus maintaining a high free-droplet concentration. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
106
issue
10
pages
2533 - 2544
publisher
The American Chemical Society
external identifiers
  • wos:000174369400017
  • scopus:0037075814
ISSN
1520-5207
DOI
10.1021/jp0139235
language
English
LU publication?
yes
id
a33f5035-6c7d-4b5a-8e2a-fcbc4e23558f (old id 342016)
date added to LUP
2007-10-22 09:59:17
date last changed
2017-01-01 06:49:06
@article{a33f5035-6c7d-4b5a-8e2a-fcbc4e23558f,
  abstract     = {Mixtures of an amphiphilic graft copolymer in water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/cyclohexane oil-continuous microemulsions are studied by the PGSE NMR technique and by viscometry. The graft copolymer has an oil-soluble poly(dodecyl methacrylate) backbone and water-soluble poly(ethylene glycol) side chains. Water, surfactant, and polymer self-diffusion coefficients can be measured individually by PGSE NMR. The water and the surfactant self-diffusion coefficients are equal, and both monitor the overall diffusion of the water droplets of the microemulsion. The graft copolymer enhances the microemulsion viscosity (relative increase = 2000), and large viscosifying effects are promoted by increased degrees of grafting, increased polymer concentration, and large water droplets. Systems with high viscosities always display slow polymer self-diffusion. The droplet diffusion is always much more rapid than the polymer diffusion; thus, the polymer molecules do not immobilize the droplets. The results give the following microscopic picture of the mixtures. Polydisperse, but mostly finite, polymer-droplet aggregates coexist with a large fraction (30%) of "free" droplets. The aggregate size varies strongly with the polymer concentration, but only at the highest polymer concentration investigated (28 g/dm(3)) is there evidence of a fraction of very large (possibly infinite) aggregates. If the polymer/droplet ratio is increased, or if the mixture is diluted by oil, the system responds by inserting more polymer side chains per bound droplet, thus maintaining a high free-droplet concentration.},
  author       = {Holmberg, A and Piculell, Lennart and Nyden, M},
  issn         = {1520-5207},
  language     = {eng},
  number       = {10},
  pages        = {2533--2544},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Effects of an amphiphilic graft copolymer on an oil-continuous microemulsion. Molecular self-diffusion and viscosity},
  url          = {http://dx.doi.org/10.1021/jp0139235},
  volume       = {106},
  year         = {2002},
}