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Kinetics of oil solubilization in microemulsion droplets. Mechanism of oil transport.

Evilevitch, Alex LU ; Olsson, Ulf LU ; Jönsson, Bengt LU and Wennerström, Håkan LU (2001) In Electroanalysis 16(23). p.8755-8762
Abstract
We have studied the kinetics of the solubilization of oil through a temperature jump into a droplet microemulsion phase in the system water-pentaethylene oxide dodecyl ether-decane at 25 C. The initial state is formed by subjecting the equilibrium system at 25 C to a temperature quench to 22, 20, and 14 C, respectively. At this lower temperature, which at equilibrium corresponds to a two-phase system, oil droplets form and grow in size with increasing time. By varying the time between the quench and the T-jump, the size of the initial oil drops is varied in a systematic and known way in the relaxation study. The relaxation process is monitored by following the turbidity of the system. We find that for all the systems the relaxation back to... (More)
We have studied the kinetics of the solubilization of oil through a temperature jump into a droplet microemulsion phase in the system water-pentaethylene oxide dodecyl ether-decane at 25 C. The initial state is formed by subjecting the equilibrium system at 25 C to a temperature quench to 22, 20, and 14 C, respectively. At this lower temperature, which at equilibrium corresponds to a two-phase system, oil droplets form and grow in size with increasing time. By varying the time between the quench and the T-jump, the size of the initial oil drops is varied in a systematic and known way in the relaxation study. The relaxation process is monitored by following the turbidity of the system. We find that for all the systems the relaxation back to equlibrium is much faster than the drop growth process observed after the temperature quench. This general observation is explained by realizing that the redissolution of the oil drops is analogous to the oil transfer phase, which in the quench experiment occurs prior to the Ostwald ripening phase. More significant is that we observed a qualitative transition in the relaxation behavior when the initial aggregate distribution is varied. In all cases we have the same initial temperature and overall composition and one population of many small droplets and fewer larger drops. The size of the larger drops only affects the relaxation in a quantitative way. If the small droplets are only slightly smaller than the equilibrium size, equilibration occurs through the diffusion of oil molecules in the bulk phase. When the initial droplets are sufficiently small, a new kinetic route is available where there is an efficient direct oil transfer between the small droplets and large drops. This allows for a fast relaxation of the oil distribution between the two populations of drops. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Electroanalysis
volume
16
issue
23
pages
8755 - 8762
publisher
John Wiley & Sons
external identifiers
  • scopus:0034321130
ISSN
1040-0397
DOI
10.1021/la000511z
language
English
LU publication?
yes
id
ed4a4005-f3ec-4f4a-a335-a92360100349 (old id 947846)
date added to LUP
2008-01-24 17:39:32
date last changed
2018-05-29 10:07:38
@article{ed4a4005-f3ec-4f4a-a335-a92360100349,
  abstract     = {We have studied the kinetics of the solubilization of oil through a temperature jump into a droplet microemulsion phase in the system water-pentaethylene oxide dodecyl ether-decane at 25 C. The initial state is formed by subjecting the equilibrium system at 25 C to a temperature quench to 22, 20, and 14 C, respectively. At this lower temperature, which at equilibrium corresponds to a two-phase system, oil droplets form and grow in size with increasing time. By varying the time between the quench and the T-jump, the size of the initial oil drops is varied in a systematic and known way in the relaxation study. The relaxation process is monitored by following the turbidity of the system. We find that for all the systems the relaxation back to equlibrium is much faster than the drop growth process observed after the temperature quench. This general observation is explained by realizing that the redissolution of the oil drops is analogous to the oil transfer phase, which in the quench experiment occurs prior to the Ostwald ripening phase. More significant is that we observed a qualitative transition in the relaxation behavior when the initial aggregate distribution is varied. In all cases we have the same initial temperature and overall composition and one population of many small droplets and fewer larger drops. The size of the larger drops only affects the relaxation in a quantitative way. If the small droplets are only slightly smaller than the equilibrium size, equilibration occurs through the diffusion of oil molecules in the bulk phase. When the initial droplets are sufficiently small, a new kinetic route is available where there is an efficient direct oil transfer between the small droplets and large drops. This allows for a fast relaxation of the oil distribution between the two populations of drops.},
  author       = {Evilevitch, Alex and Olsson, Ulf and Jönsson, Bengt and Wennerström, Håkan},
  issn         = {1040-0397},
  language     = {eng},
  number       = {23},
  pages        = {8755--8762},
  publisher    = {John Wiley & Sons},
  series       = {Electroanalysis},
  title        = {Kinetics of oil solubilization in microemulsion droplets. Mechanism of oil transport.},
  url          = {http://dx.doi.org/10.1021/la000511z},
  volume       = {16},
  year         = {2001},
}