Characterization by electron spin resonance of reversed micelles consisting of the ternary system AOT-isooctane-water

Haering, Gabriel; Luisi, Pier Luigi; Häuser, H.

doi:10.1021/j100323a050

Cited by 77 publications

(63 citation statements)

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“…[1][2][3][4][5][6][7][8][9][10] Micelles serve an important scientific role as primitive structures to mimic biological structures and an important practical role for a range of biological and industrial processes. The interactions of surfactants and micelles with macromolecules and polyelectrolytes are of particular interest, since these systems include those originated by surfactants interacting with biological macromolecules, such as proteins and DNA.…”

Section: Introductionmentioning

confidence: 99%

Model for the Interactions between Anionic Dendrimers and Cationic Surfactants by Means of the Spin Probe Method

et al. 1997

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The supramolecular structures formed when anionic polyamidoamine starburst dendrimers, in the presence of low concentrations of spin probe surfactants, are added to aqueous solutions of nonlabeled cationic surfactants have been investigated by EPR spectroscopy. In order to obtain an overview of dendrimer/surfactant systems, a variety of spin probe surfactants, differing from one another in chain length, structure, polarity, charge, solubility, and self-aggregating ability, were employed. Computer simulation of the experimental EPR spectra allowed evaluation of mobility and polarity parameters of the spin probes in the supramolecular structures formed in addition to determination of the degree of partitioning of the probe among various supramolecular structures. Depending on the concentrations of both the surfactant and the dendrimer, the dendrimer size, and temperature, the model envisions two types of structures, i.e., primary structures consisting of probe monomers adsorbed on the dendrimer surface and secondary structures consisting of probe monomers adsorbed in surfactant aggregates bound to the dendrimer surface. Depending on the probe concentration and on the probe solubility into the surfactant aggregates, line broadening was observed, which was consistent with spin-spin interactions supporting a model in which more than one probe was inserted in the aggregates. This solubility was enhanced by the presence of dendrimers and by increasing temperature.

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Section: Introductionmentioning

confidence: 99%

Model for the Interactions between Anionic Dendrimers and Cationic Surfactants by Means of the Spin Probe Method

et al. 1997

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“…Both the continuous-wave Electron Paramagnetic Resonance (cw-EPR) [14][15][16][17][18][19][20][21][22] and the Electron Spin Echo (ESE) [23][24][25][26] techniques have been extensively used to study organized systems, such as micellar solutions. Recently we have applied the cw-EPR technique to investigate the supramolecular structures formed when positively charged surfactants are added to solutions of anionic SBDs [21,22,27].…”

Section: Introduetionmentioning

confidence: 99%

Interaction between Starburst Dendrimers and SDS micelles studied by continuous-wave and pulsed electron spin resonances

et al. 1997

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A computer aided analysis of both cw-and pulsed-Electron Paramagnetic Resonance (EPR) spectra of 5doxylstearic acid (5DXSA) as a probe was carried out to compare the aggregation process of Sodium Dodecyl Sulfate (SDS) surfactants in the absence and in the presence of Starburst Dendrimers (SBDs), and to provide information on the interactions between SDS and SBDs. Mobility and polarity parameters were extracted from the cw-EPR analysis, whereas the analysis of the Eleetron Spin Echo Envelope Modulation (ESEEM) signal provided details about the doxyl environment in the SDS mieeUes. In the absence of SBDs, the formation of SDS mieelles was revealed by the decrease in mobility of the probes inserted in the micelles. The high packing of SDS chains in the rniceUes prevented the water permeability at the doxyl site. In the presence of the dend¡ the analysis of the EPR spectra suggested the formation of SDS aggregates at the dendfimer surface (cooperative interaction). The larger the size of the dendrimers and the protonation of their surface, the stronger the interactions resulted between the SDS surfactants and the SBD surface. The analysis of the ESEEM pattern indicated that the cooperative interaction of the surfaetant with the SBD surface led to a less packed structure of the aggregates. A schematic view was proposed to describe the local structure of the doxyl group and its environment in the absenee and in the presence of the dendrimers.

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“…The initial increase in the water uptake aqueous phase to the water pool of reverse micelles is govwith an increase in cosurfactant concentration, in the absence erned by the partition coefficient, L i , for each salt, of an electrolyte, is a characteristic of the titration method, but is not obtainable using the contact method. When reverse L i Å C U i /C i , [2] micelles were formed by the titration and contact methods using identical aqueous solutions, higher water uptakes were where C V i is the concentration of salt in the water pool, and obtained via contact. C i is the concentration of salt in the excess aqueous phase.…”

Section: Discussionmentioning

confidence: 99%

“…The titration method has been used widely to form reverse containing large amounts of water without the addition of a micelles as injection fluids for a number of tertiary oil recovcosurfactant (2)(3)(4)(5). On the other hand, cationic surfactants ery processes (21) and to study different types of reactions inside the reverse micelles (5).…”

Section: Introductionmentioning

confidence: 99%

Comparison of the Titration and Contact Methods for the Water Solubilization Capacity of AOT Reverse Micelles in the Presence of a Cosurfactant

Rabie

Helou

Weber

et al. 1997

Journal of Colloid and Interface Science

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Characterization by electron spin resonance of reversed micelles consisting of the ternary system AOT-isooctane-water

Cited by 77 publications

References 0 publications

Model for the Interactions between Anionic Dendrimers and Cationic Surfactants by Means of the Spin Probe Method

Model for the Interactions between Anionic Dendrimers and Cationic Surfactants by Means of the Spin Probe Method

Interaction between Starburst Dendrimers and SDS micelles studied by continuous-wave and pulsed electron spin resonances

Comparison of the Titration and Contact Methods for the Water Solubilization Capacity of AOT Reverse Micelles in the Presence of a Cosurfactant

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