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Marcus, J. ; Touraud, Didier ; Prevost, S. ; Diat, O. ; Zemb, T. ; Kunz, Werner

Influence of additives on the structure of surfactant-free microemulsions

Marcus, J., Touraud, Didier, Prevost, S., Diat, O., Zemb, T. and Kunz, Werner (2015) Influence of additives on the structure of surfactant-free microemulsions. Phys.Chem.Chem.Phys. 17, p. 32528.

Date of publication of this fulltext: 08 Feb 2016 13:59
Article
DOI to cite this document: 10.5283/epub.33261


Abstract

We study the addition of electrolytes to surfactant-free microemulsions in the domain where polydisperse pre-Ouzo aggregates are present. As in previous studies, the microemulsion is the ternary system water/ethanol/1-octanol, where ethanol acts as co-solvent. Addition of electrolytes modifies the static X-ray and neutron scattering, and dynamic light scattering patterns, as well as the position ...

We study the addition of electrolytes to surfactant-free microemulsions in the domain where polydisperse pre-Ouzo aggregates are present. As in previous studies, the microemulsion is the ternary system water/ethanol/1-octanol, where ethanol acts as co-solvent. Addition of electrolytes modifies the static X-ray and neutron scattering, and dynamic light scattering patterns, as well as the position of the miscibility gap, where spontaneous emulsification occurs upon dilution with water. All observations can be rationalized considering that electrolytes are either “salting out” the ethanol, which is the main component of the interface stabilizing the aggregates, or producing charge separation via the antagonistic ion effect discovered by Onuki et al. Amphiphilic electrolytes, such as sodium dodecylsulfate or sodium dietheylhexylphosphate, induce a gradual transition towards monodisperse ionic micelles with their characteristic broad scattering “peak”. In these micelles the ethanol plays then the role of a cosurfactant. Dynamic light scattering can only be understood by combination of fluctuations of aggregate concentration due to the vicinity of a critical point and in-out fluctuations of ethanol.



Involved Institutions


Details

Item typeArticle
Journal or Publication TitlePhys.Chem.Chem.Phys.
Publisher:Royal Society of Chemistry (RSC)
Volume:17
Page Range:p. 32528
Date2015
Additional Information (public)Open Access Komponente aus der Allianzlizenz
InstitutionsChemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry VI - Physical Chemistry (Solution Chemistry) > Prof. Dr. Werner Kunz
Identification Number
ValueType
10.1039/C5CP06364GDOI
Keywordsmicroemulsion stability electrolyte emulsification
Dewey Decimal Classification500 Science > 540 Chemistry & allied sciences
StatusPublished
RefereedYes, this version has been refereed
Created at the University of RegensburgYes
URN of the UB Regensburgurn:nbn:de:bvb:355-epub-332612
Item ID33261

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