AOT microemulsions: droplet size and clustering in the temperature range between the supercooled state and the upper phase boundary

Domschke, Markus; Kraska, Martin; Feile, R.; Stühn, Bernd

doi:10.1039/c3sm51632f

Cited by 21 publications

(32 citation statements)

References 54 publications

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“…The ratio between them determines the preferred curvature revealing that the increase of the hydrophobic tails outweighs the increase of the hydrophilic heads. This finding is phenomenologically summarized through [5] R pol = 4.13 Å − 0.01…”

Section: Fig 25mentioning

confidence: 92%

“…This is surprising, as for instance the assumption of a AOT being independent of the size of the droplets might considered to be too simple. In fact it has been discussed that a AOT is weakly dependent on ω [21], the water to oil ratio [22] and also on temperature [5]. Since the polar radius does not appear to depend on molecular parameters of the oil it is expected that to a first approximation the droplet structure is only determined by the ratio of water to surfactant.…”

Section: Fig 25mentioning

confidence: 97%

“…To explain this phenomenon two different Extracted from small angle neutron scattering data (oils: n-heptane-d16, toluene-d8) [3]. Right Extracted from small angle X-ray scattering data (oil: n-decane) [5]. The shaded area marks the R c , T -area where an excess ice phase exists.…”

Section: Supercooling Of Water Confined In Dropletsmentioning

confidence: 98%

“…2.5. Right Effective head group area a AOT and polar head group volume ν SO − 3 [5]. Reproduced by permission of The Royal Society of Chemistry that the phenomenon of percolation (discussed in Sect.…”

Section: Fig 25mentioning

confidence: 99%

“…In AOT microemulsions a very stable w/o droplet phase exists in a wide range of compositions and temperatures. The droplet phase microemulsions have been thoroughly studied in the past decades for instance to test liquid state theories [1], to study dynamics of droplets and surfactant layers [2,3], droplet aggregation [4,5], dynamic percolation [6,7] and in particular to study polymer loaded droplets [8]. These aspects will be discussed in the following sections.…”

Section: Stability and Phase Diagramsmentioning

confidence: 99%

See 4 more Smart Citations

Aggregate Structure and Dynamic Percolation in Microemulsions

Kraska

Kuttich

Stühn

2015

Bottom-Up Self-Organization in Supramolecular Soft Matter

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This contribution deals with a special class of soft matter systems called microemulsions. They are mixtures of oil and water stabilized with a surfactant. The stabilisation is achieved through the reduction of interfacial tension by the amphiphilic surfactant. They thus consist of oil and water phases separated by a surfactant layer. The nanoscopic structure of these phases, in particular that of spherical nano droplets, is analysed in this chapter. The impact of temperature and mixing ratio of the constituents is shown. The fascinating phenomenon of dynamic droplet percolation and aggregation near a temperature induced phase separation are discussed. Microemulsions provide an excellent model system for the investigation of confinement effects on molecules. Conversely these guest molecules modify structural and dynamical properties of the microemulsion. This may even lead to the formation of transient networks with short time gel-like and long time self-diffusion dynamics of droplets.

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Section: Fig 25mentioning

confidence: 92%

Section: Fig 25mentioning

confidence: 97%

Section: Supercooling Of Water Confined In Dropletsmentioning

confidence: 98%

Section: Fig 25mentioning

confidence: 99%

Section: Stability and Phase Diagramsmentioning

confidence: 99%

See 3 more Smart Citations

Aggregate Structure and Dynamic Percolation in Microemulsions

Kraska

Kuttich

Stühn

2015

Bottom-Up Self-Organization in Supramolecular Soft Matter

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Micropolarity and Hydrogen‐Bond Donor Ability of Environmentally Friendly Anionic Reverse Micelles Explored by UV/Vis Absorption of a Molecular Probe and FTIR Spectroscopy

et al. 2018

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In the present work we show how two biocompatible solvents, methyl laurate (ML) and isopropyl myristate (IPM), can be used as a less toxic alternative to replace the nonpolar component in a sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) reverse micelles (RMs) formulation. In this sense, the micropolarity and the hydrogen-bond ability of the interface were monitored through the use of the solvatochromism of a molecular probe (1-methyl-8-oxyquinolinium betaine, QB) and Fourier transform infrared spectroscopy (FTIR). Our results demonstrate that the micropolarity sensed by QB in ML RMs is lower than in IPM RMs. Additionally, the water molecules form stronger H-bond interactions with the polar head of AOT in ML than in IPM. By FTIR was revealed that more water molecules interact with the interface in ML/AOT RMs. On the other hand, for AOT RMs generated in IPM, the weaker water-surfactant interaction allows the water molecules to establish hydrogen bonds with each other trending to bulk water more easily than in ML RMs, a consequence of the dissimilar penetration of nonpolar solvents into the interfacial region. The penetration process is strongly controlled by the polarity and viscosity of the external solvents. All of these results allow us to characterize these biocompatible systems, providing information about interfacial properties and how they can be altered by changing the external solvent. The ability of the nontoxic solvent to penetrate or not into the AOT interface produces a new interface with attractive properties.

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Experimental and Theoretical Efforts to Identify the Microstructural Transition of Water to Acetonitrile‐Based Reverse Micelle through Binary Compositions of Polar Solvents

et al. 2017

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The present report was undertaken due to the scarcity of information regarding the microstructural transition from aqueous to acetonitrile (ACN)‐based non‐aqueous reverse micelles (RMs) stabilized by cationic didodecyldimethylammonium bromide (DDAB) and anionic sodium bis(2‐ethylhexyl) sulfosuccinate (AOT) in cyclohexane. The synergistic solubilization capacity of corresponding polar solvent at a fixed composition and the nature of conductance plots in these RMs were markedly varied along with the composition of binary solvents (water and ACN at pure or mixed states) and the surfactant charge types (DDAB and AOT). The structural alteration in these RMs through water‐ and ACN‐rich compositions were studied by FTIR, where the results were explained in terms of molecular states of water and ACN inside RMs. The differential binding affinity of both polar solvents with the two surfactants was shown using ab initio calculations. The subsequent appearance and disappearance of aqueous nano‐pool was verified from UV‐Vis technique using CoCl2. The lack of H‐bonding ability on going from aqueous to ACN‐based RMs was evidenced from the temperature‐dependent DLS study along with the absorption profiles of 7‐hydroxycoumarin. The results showed how the microstructures and H‐bonding interactions inside RMs are dramatically altered by simply changing polarity of the solvents or the surfactant charge‐types. This report could be useful to understand the formation mechanism of two class of RMs.

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AOT microemulsions: droplet size and clustering in the temperature range between the supercooled state and the upper phase boundary

Cited by 21 publications

References 54 publications

Aggregate Structure and Dynamic Percolation in Microemulsions

Aggregate Structure and Dynamic Percolation in Microemulsions

Micropolarity and Hydrogen‐Bond Donor Ability of Environmentally Friendly Anionic Reverse Micelles Explored by UV/Vis Absorption of a Molecular Probe and FTIR Spectroscopy

Experimental and Theoretical Efforts to Identify the Microstructural Transition of Water to Acetonitrile‐Based Reverse Micelle through Binary Compositions of Polar Solvents

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