How to study microemulsions

Kahlweit, M.; Strey, R.; Haase, Dirk; Kunieda, H.; Schmeling, T.; Faulhaber, B.; Borkovec, Michal; Eicke, Hans‐Friedrich; Busse, G.; Eggers, F.; Funck, Theodor; Richmann, H.; Magid, L. J.; Söderman, Olle; Stilbs, Peter; Winkler, Jay R.; Dittrich, A.; Jahn, Wolfgang

doi:10.1016/0021-9797(87)90480-2

Cited by 287 publications

(175 citation statements)

References 25 publications

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“…5 (right) a decrease of  leads to a shift of the phase diagrams to lower temperatures and surfactant concentrations, which is always the case for non-ionic microemulsions. 1,14,15 What is remarkable is the fact that the sol-gel transition boundary also shifts to lower temperatures with decreasing  although the gelator concentration in the oil phase is kept constant. Moreover, the lower  the more difficult it was to gel the microemulsion.…”

Section: Figmentioning

confidence: 99%

Gelled polymerizable microemulsions. Part 3 Rheology

et al. 2009

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The UCD community has made this article openly available. Please share how this access benefits you. Your story matters! (@ucd_oa) Some rights reserved. For more information, please see the item record link above. AbstractThis is the first report on the rheological properties of oil-gelled polymerizable bicontinuous microemulsions. The polymerizable base system consists of H 2 O / NIPAm / BisAm -ndodecane -C 13/15 E 5 (a technical grade n-alkyl polyglycol ether), where NIPAm denotes the monomer N-isopropylacrylamide and BisAm the cross-linker N,N′-methylene bisacrylamide.For the planned polymerization of the aqueous phase a scaffold is needed to preserve the structure of the templating microemulsion during the polymerization. This scaffold is supposed to be a gel, which was formed by adding the gelator 12-hydroxyoctadecanoic acid (12-HOA) to the oil phase of the microemulsion. The influence of the water-to-oil ratio , of the gelator concentration , and of the monomer concentration  on the rheological behavior of gelled microemulsions has been studied in detail. The most important result of the study at hand is the observation of a transition from a high viscous solution to a gel, i.e. from a transient to a permanent network, with increasing gelator concentration and increasing amount of the oil phase, respectively. In other words, it is only under well-defined conditions that an oil-gelled microemulsion is formed. * corresponding author: luis.magno@ucd.ie, phone/fax: +353-1-716-1691/1177 1 To review the final edited and published work see http://dx

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Section: Figmentioning

confidence: 99%

Gelled polymerizable microemulsions. Part 3 Rheology

et al. 2009

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“…They show thermodynamic stability, optical clarity and high solubilization capacity, 1 and are isotropic with ultralow interfacial tension. 2,3 Usually, microemulsions are mixtures of non-polar solvents with polar liquids like water stabilized by a surfactant, 4,5 frequently in combination with a cosurfactant -often a short or medium chain alcohol 6 -forming an interfacial film that separates the two, in principle immiscible, solvents. 7 Though they are macroscopically homogeneous solutions, an ordered structure can be found on the nanoscopic scale such as oil-in-water (o/w) or water-in-oil (w/o) droplets, similar to the structures of micelles, [8][9][10] but with droplet sizes of 100 nm.…”

Section: Introductionmentioning

confidence: 99%

Microemulsions with renewable feedstock oils

2012

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In this paper we discuss the influence of chemical structures of renewable feedstock oils (RFOs) on the domains of existence and the nano-structures of microemulsions. We compare the results to those of classical microemulsions containing classical n-alkanes. First, the domains of microemulsions obtained from the melt of water, sodium dodecyl sulfate (SDS) as surfactant, 1-pentanol as co-surfactant and different RFOs (or RFO melts) in pseudo-ternary phase diagrams are presented. A surfactantco-surfactant mass ratio of 1 : 2 is kept constant and the RFO (or RFO melt) is considered as a pseudo-constituent. Two different fatty methyl ester (FAME) biodiesels from rapeseed and cuphea oils, rapeseed oil, "TBK" biodiesel from rapeseed oil, limonene, and different mixtures of limonene to FAME-rapeseed biodiesel and FAME-rapeseed biodiesel to FAME-cuphea biodiesel are used as RFOs or RFO melts. Second, conductivity data are shown along an experimental path having a constant RFO or RFO melt : (surfactant-co-surfactant) mass ratio, whereas the water content is varied. All obtained data are then compared to data from previous studies with a series of n-alkanes (from n-hexane to n-hexadecane). As the main conclusion it is found that RFOs or RFO melts can easily substitute n-alkanes. From the chemical structure of the oils, it appears that not only the polarity of the oil plays an important role but also does the absolute size of the oil molecules. In all cases microemulsion systems exhibit percolative behavior.

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“…For short-chain surfactants, the microemulsion phase always wets the oil-water interface. For longer-chain surfactants, on the other hand, the microemulsion does not wet close to the phase-inversion temperature 18 -where it contains exactly equal amounts of oil and water-while it wets when the upper or lower critical end points are approached, at which the microemulsion merges with the oil-rich or water-rich phase, respectively. 19,20 This behavior can be understood theoretically very well on the basis of a Ginzburg-Landau model with a single, scalar order parameter, which is to be identified with the local concentration difference of oil and water.…”

Section: Introductionmentioning

confidence: 96%

Wetting in ternary mixtures—with and without amphiphiles

Schilling

Gompper

2002

The Journal of Chemical Physics

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The interfacial wetting behavior of ternary fluid mixtures is investigated, both for systems where all components have isotropic interaction potentials, as well as for systems where one component is an amphiphile. The BEG model and the corresponding two-order-parameter Ginzburg-Landau model are employed for systems without amphiphiles. We calculate the global wetting phase diagram for nonamphiphilic mixtures. In the investigated range of interaction parameters, the wetting transitions are always continuous at three-phase coexistence. The critical behavior is found to be universal in some, nonuniversal in other parts of the phase diagram. For systems with amphiphiles, two additional interaction terms are taken into account. The first models the aggregation of amphiphilic molecules at the air-water interface, the second the formation of amphiphilic bilayers in water. We find that the first term leads to a reduction of the tension of the air-water interface, and favors wetting by the water-rich phase, while the second-bilayer-term leads to a reduction of the tension of the interface between the water-rich and amphiphile-rich phases.

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How to study microemulsions

Cited by 287 publications

References 25 publications

Gelled polymerizable microemulsions. Part 3 Rheology

Gelled polymerizable microemulsions. Part 3 Rheology

Microemulsions with renewable feedstock oils

Wetting in ternary mixtures—with and without amphiphiles

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