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Ulf Olsson. Portrait.

Ulf Olsson

Professor

Ulf Olsson. Portrait.

From bilayers to micelles in a dilute surfactant system: a phase with a perforated bilayer network

Author

  • Marcus Rasmusson
  • Ulf Olsson

Summary, in English

The quaternary system comprising sodium dodecyl sulfate/water/pentanol/dodecane has been studied at high oil content and at two different water-to-surfactant ratios. Of particular interest is a highly flow birefringent, isotropic fluid phase, which occupies an island in the pseudo-ternary phase diagrams between the L<sub>2</sub> phase and the L<sub>3</sub> phase and which is in close proximity to the dilute lamellar phase. In order to investigate its microstructure, the self-diffusion coefficient of the solvent was measured in this phase using Fourier transform pulsed-field-gradient spin-echo NMR spectroscopy, and its value was found to be significantly lower than those in the L<sub>3</sub> phase of the same system. Comparative conductivity measurements were also performed, and they showed that the conducting material in the phase forms an infinitely connected network. In conclusion, it seems reasonable to describe the phase microstructure as a connected perforated bilayer or possibly a connected three-dimensional network of reverse cylinders. The conductivity of the L<sub>x</sub> phase decreases strongly upon stirring. Taking into account the flow birefringence, this is interpreted as a shear-induced phase transition to a lamellar phase

Department/s

  • Physical Chemistry

Publishing year

2002

Language

English

Pages

74-82

Publication/Series

Progress in Colloid &amp; Polymer Science

Volume

120

Document type

Paper in conference proceeding

Topic

  • Chemical Sciences

Keywords

  • self-assembly structures
  • sodium dodecyl sulfate-water-pentanol-dodecane
  • quaternary system
  • high oil content
  • water-to-surfactant ratios
  • dilute surfactant system
  • bilayers
  • micelles
  • perforated bilayer network
  • highly flow birefringent phase
  • isotropic fluid phase
  • pseudo-ternary phase diagrams
  • self-diffusion coefficient
  • Fourier transform spin-echo NMR
  • three-dimensional network
  • phase microstructure
  • free energy
  • swelling
  • flexible surfactant bilayers
  • small angle X-ray scattering
  • reverse cylinders
  • parallel oriented monolayers
  • oppositely oriented monolayers

Conference name

Conference on Lipid and Polymer-Lipid Systems, 2002

Conference date

2002-10-01 - 2002-10-02

Conference place

Chia Laguna, Italy

Status

Published

Report number

120

ISBN/ISSN/Other

  • ISSN: 0340-255X