Study of micelle formation in solutions of alkylammonium carboxylates in apolar solvents by positron annihilation techniques

Fucugauchi, Luz Alicia; Djermouni, Belkacem; Handel, Edward D.; Ache, Hans J.

doi:10.1021/ja00505a006

Cited by 31 publications

(7 citation statements)

References 1 publication

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“…The effect of the nature of the oil phase, or a polar solvent, in this case aliphatic vs. aromatic hydrocarbon, is interesting and may be related to strong intermolecular interaction between the solvent molecules and the surfactant molecules, similar to the one which we suggested for the dodecylammonium benzoate system in benzene solution. 18 Another point of interest is the characteristic behavior of Z2 at higher water concentrations in the potassium oleate-hexadecane-1 -hexanol-water system. Shah interpreted his electrical resistance, viscosity, and NMR measurements in the birefringent region, i.e., at a water/oil ratio between 0.7 and 1.3, in terms of a change in the structure of water from water spheres to water cylinders to water lamellae.…”

Section: Resultsmentioning

confidence: 99%

Microemulsion systems studied by positron annihilation techniques

Boussaha¹,

Djermouni²,

Fucugauchi³

et al. 1980

J. Am. Chem. Soc.

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The formation of thermalized positronium atoms is greatly reduced if increasing amounts of water become solubilized in reversed micelles formed by sodium bis(2-ethylhexyl) sulfosuccinate in apolar solvents. Similar observations have been made if the surfactant is Triton X-100. The application of the positron annihilation technique to the study of microemulsions consisting of potassium oleate-alcohol-oil-water mixtures indicates, consistent with previous results, that microemulsion formation requires a certain water/oil ratio if the oil is a long-chain aliphatic hydrocarbon such as hexadecane. This ratio is 0.4 in the case of a 1-pentanol-and 0.2 for a 1-hexanol-containing mixture. This minimum water content is strongly reduced if the oil is an aromatic hydrocarbon. The positron annihilation data also sensitively reflect structural rearrangements in these solutions occurring upon further addition of water, such as the transition of spherical aggregates to a disk-like lamellae structure.

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Section: Resultsmentioning

confidence: 99%

Microemulsion systems studied by positron annihilation techniques

Boussaha¹,

Djermouni²,

Fucugauchi³

et al. 1980

J. Am. Chem. Soc.

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“…3 are present in biomembranes, for which parallel structures have been identified. 15,16 The most prolific area of research utilising PALS for self-assembled systems is in micellar 4,6,7,8,10,11,[58][59][60][61][62][63] and microemulsion systems. 24,[52][53][54] Although the exact mechanisms for the formation of such morphologies are unknown, they are widely associated with membrane re-arrangements resulting from cellular stress and are implicated for inter/intra cellular trafficking.…”

Section: Fitting Pals Spectramentioning

confidence: 99%

“…There is also some evidence that the oPs preferentially associates in the hydrophobic domain, presumably in the inter-chain regions, rather than in the aqueous phase. 15,16 The most prolific area of research utilising PALS for self-assembled systems is in micellar 4,6,7,8,10,11,[58][59][60][61][62][63] and microemulsion systems. [64][65][66][67] However, it is not always easy to interpret the findings in this area for reasons already stated above and a better understanding of the properties and behaviour of the positronium is necessary.…”

Section: Application Of Pals To Investigation Of Lipid Self-assembly ...mentioning

confidence: 99%

Positron annihilation lifetime spectroscopy (PALS): a probe for molecular organisation in self-assembled biomimetic systems

Fong

Dong

Hill

et al. 2015

Phys. Chem. Chem. Phys.

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Positron annihilation lifetime spectroscopy (PALS) has been shown to be highly sensitive to conformational, structural and microenvironmental transformations arising from subtle geometric changes in molecular geometry in self-assembling biomimetic systems. The ortho-positronium (oPs) may be considered an active probe that can provide information on intrinsic packing and mobility within low molecular weight solids, viscous liquids, and soft matter systems. In this perspective we provide a critical overview of the literature in this field, including the evolution of analysis software and experimental protocols with commentary upon the practical utility of PALS. In particular, we discuss how PALS can provide unique insight into the macroscopic transport properties of several porous biomembrane-like nanostructures and suggest how this insight may provide information on the release of drugs from these matrices to aid in developing therapeutic interventions. We discuss the potentially exciting and fruitful application of this technique to membrane dynamics, diffusion and permeability. We propose that PALS can provide novel molecular level information that is complementary to conventional characterisation techniques.

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“…Their predictions help analyze many important properties related with the micellization processes such as size, shape, surface roughness, and the internal structure of micelles. In fact, these studies have assisted in explaining previous experimental results [32,40]. Yet not many simulation studies have explored the phenomenon of surfactant self-assembly in nonpolar solvents, which results in the formation of RMs [47 -49].…”

Section: Introductionmentioning

confidence: 99%

Self – assembly of model surfactants as reverse micelles in nonpolar solvents and their role as interfacial tension modifiers

Mayoral

Arcos-Casarrubias

Goicochea

2021

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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The self-assembly of linear surfactants into reverse micelles (RMs) in nonpolar solvents, and their efficiency in reducing the interfacial tension is studied using dissipative particle dynamic simulations. Given the importance of RMs as thickeners, among many other applications, their properties are studied here when formed in oil and in supercritical carbon dioxide (scCO2). Our simulations are found to be in agreement with experimental results of surfactant self-assembly in scCO2 that found viscosity increments of up to 90% with 10 wt % of surfactants. The role played by a small number of water molecules in RM formation is studied as well in both solvents, corroborating experiments reporting the enhancement of RM formation with the addition of a small quantity of water. The dynamics of water surfactant aggregation in nonpolar solvents is also discussed. Lastly, the performance of the model surfactant as an interfacial tension modifier is studied in detail. The results show that RMs are more easily formed in oil than in scCO2 and that the effectiveness of the surfactant in reducing the interfacial tension lies in its preference to adsorb at interfaces rather than selfassociation.

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Study of micelle formation in solutions of alkylammonium carboxylates in apolar solvents by positron annihilation techniques

Cited by 31 publications

References 1 publication

Microemulsion systems studied by positron annihilation techniques

Microemulsion systems studied by positron annihilation techniques

Positron annihilation lifetime spectroscopy (PALS): a probe for molecular organisation in self-assembled biomimetic systems

Self – assembly of model surfactants as reverse micelles in nonpolar solvents and their role as interfacial tension modifiers

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