Small-angle neutron scattering from lecithin reverse micelles

Aliotta, F.; Fontanella, M. E.; Sacchi, M.; Vasi, C.; Manna, Gianfranco La; Turco-Liveri, V.

doi:10.1016/s0022-2860(96)09274-5

Cited by 13 publications

(7 citation statements)

References 10 publications

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“…The mean micellar core radius of the dry lecithin reverse micelles obtained here (18.1 Å) can be considered in good agreement with the micellar radius previously found (25 Å) by small-angle neutron scattering technique, if the contribution given to the micellar size by the surfactant alkyl chains is accounted for …”

Section: Resultssupporting

confidence: 90%

Spectroscopic and Structural Investigation of the Confinement of d and l Dimethyl Tartrate in Lecithin Reverse Micelles

Abbate¹,

Castiglione²,

Longhi³

et al. 2009

J. Phys. Chem. B

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The confinement of D and L dimethyl tartrate in lecithin reverse micelles dispersed in cyclohexane has been investigated by FT-IR, polarimetry, electronic and vibrational circular dichroism (ECD and VCD), 1H NMR, and small-angle X-ray scattering (SAXS). Measurements have been performed at room temperature as a function of the solubilizate-to-surfactant molar ratio (R) at fixed lecithin concentration. The analysis of experimental data indicates that the dimethyl tartrate molecules are solubilized within reverse micelles in proximity to the surfactant head groups in the same way for the D and L forms. The encapsulation of dimethyl tatrate within lecithin reverse micelles involves changes in its H-bonds, from what is observed in the pure solid or in CCl4 solutions; this is a consequence of the establishment of specific solute-surfactant headgroup interactions and of confinement effects. In the 0 < or = R < or = 1.7 range, SAXS profiles of dimethyl tartrate/lecithin/ cyclohexane micellar solutions are well-described by a model of interacting polydisperse spherical micellar cores whose mean radius does not change appreciably with R (i.e., it changes from about 18 to 20 angstroms). 1H NMR diffusion measurements of both dimethyl tartrates and lecithin were rationalized in terms of collective translational motions of the entire micellar aggregate and of their molecular diffusion among clusters of reverse micelles. The association of optically active lecithin with D and L dimethyl tartrate leads to the formation of self-organized supramolecular aggregates whose interesting chiroptical features are evidenced by polarimetry and CD.

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Section: Resultssupporting

confidence: 90%

Spectroscopic and Structural Investigation of the Confinement of d and l Dimethyl Tartrate in Lecithin Reverse Micelles

Abbate¹,

Castiglione²,

Longhi³

et al. 2009

J. Phys. Chem. B

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“…The derived parameters, obtained following the fitting procedure previously described, are the micellar core mean radius ( r m ); the local volume fraction of scattering objects (η), whose deviation from the mean volume fraction is a measure of the intermicellar interactions; and the parameter b , which is a quantitative descriptor of the size polydispersity. Larger b values indicate lower size polydispersion. , Concerning the Gaussian curve, the parameters of interest are the peak position ( q max ) and its full-width at half-maximum (Δ q max ). All these quantities are collected in Table .…”

Section: Resultsmentioning

confidence: 99%

“…Larger b values indicate lower size polydispersion. 22,23 Concerning the Gaussian curve, the parameters of interest are the peak position (q max ) and its full-width at half-maximum (∆q max ). All these quantities are collected in Table 1.…”

Section: Saxs Analysismentioning

confidence: 99%

Structural Characterization of Frozen n-Heptane Solutions of Metal-Containing Reverse Micelles

et al. 2007

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The microstructure of temperature-quenched solutions of reverse micelles formed by sodium, cobalt, ytterbium, and cobalt/ytterbium bis(2-ethylhexyl)sulfosuccinate in n-heptane has been investigated by SAXS and EXAFS. Some changes in the X-ray absorption spectra with respect to the same systems at room temperature have been observed. The analysis of the SAXS spectra leads to the hypothesis that at 77 K the closed spherical structure of reverse micelles is retained and that during the temperature quench they undergo a clustering process involving the transition from a quite random dispersion to the formation of more or less large clusters of strongly packed reverse micelles. This behavior is attributed to competitive effects caused by the temperature decrease. The prevalence of intermicellar attractive interactions with respect to Brownian motions leading to a collapse to more compact structure is in competition with the rapid decrease of reverse micelle diffusion rate involving a freezing of the local structures. In the case of cobalt, ytterbium, and cobalt/ytterbium bis(2-ethylhexyl)sulfosuccinate reverse micelles, further information from EXAFS measurements indicates that within the reverse micelle core exists a quite ordered nanosized domain composed of water, surfactant counterions, and oxygen atoms of the SO3- head groups. The conservation of local order and inverse structure during the clustering phenomenon that results from the fast freezing with liquid nitrogen of solutions of reverse micelles could have biological implications, i.e., the preservation of tissue samples at cryogenic temperatures.

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“…RLMs, WLMs, chains or fractals. There have been notable successes in this field, amongst them applications involving lecithins [15][16][17][18][19] (see 2 in Table 2), alkyl aluminium salts [20][21][22][23][24][25][26][27][28][29][30] 4, facial amphiphiles and bile salts, [31][32][33] such as 5 are depicted in Fig. 2.…”

Section: Self-assembling Organogelsmentioning

confidence: 99%

CO₂: a wild solvent, tamed

Cummings

Trickett

Enick

et al. 2011

Phys. Chem. Chem. Phys.

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This article reviews approaches for modification of solvent properties of supercritical carbon dioxide (scCO(2)), with particular reference to self-assembly of oligomeric and polymeric solute additives. Of special interest are viscosity modifiers for scCO(2) based on molecular self-assembly. Background on polymers and surfactants with CO(2)-compatible functionalities is covered, leading on to the attempts made so far to increase the scCO(2) viscosity, which are described in detail. The significance of this field, and the implications a breakthrough could bring environmentally and economically will be addressed.

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Small-angle neutron scattering from lecithin reverse micelles

Cited by 13 publications

References 10 publications

Spectroscopic and Structural Investigation of the Confinement of d and l Dimethyl Tartrate in Lecithin Reverse Micelles

Spectroscopic and Structural Investigation of the Confinement of d and l Dimethyl Tartrate in Lecithin Reverse Micelles

Structural Characterization of Frozen n-Heptane Solutions of Metal-Containing Reverse Micelles

CO₂: a wild solvent, tamed

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Small-angle neutron scattering from lecithin reverse micelles

Cited by 13 publications

References 10 publications

Spectroscopic and Structural Investigation of the Confinement of d and l Dimethyl Tartrate in Lecithin Reverse Micelles

Spectroscopic and Structural Investigation of the Confinement of d and l Dimethyl Tartrate in Lecithin Reverse Micelles

Structural Characterization of Frozen n-Heptane Solutions of Metal-Containing Reverse Micelles

CO2: a wild solvent, tamed

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CO₂: a wild solvent, tamed