The Branching of Reversed Polymer-like Micelles of Lecithin by Sugar-Containing Surfactants

Shchipunov, Yu. A.; Shumilina, E. V.; Ulbricht, W.; Hoffmann, H.

doi:10.1006/jcis.1998.5927

Cited by 16 publications

(6 citation statements)

References 43 publications

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“…It is obvious that the increasing exponent of G 0 departs from the theoretical value, 2.25, indicating the lower elastic property of the sample studied compared with the ideal structures and some cationic and nonionic wormlike micelles that was obtained by Shchipunov et al (1999) and Ait and Makhloufi (1999). The evolution of the relaxation time shows two breaks in the slope in Fig.…”

Section: Resultscontrasting

confidence: 44%

Effect of surfactant concentration on the formation and viscoelasticity of anionic wormlike micelle by the methods of rheology and freeze-fracture TEM

Wang

2002

Rheologica Acta

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found that the addition of salt to aqueous cationic surfactant weakens electrostatic interactions and enhances micellar growth, in which the spherical surfactant micelles undergo a transition to larger rodlike aggregations with a molar weight of about 10 6 , named as wormlike micelles. They have high surface activity, high viscosity, and the property of shear thinning, which make them have such wide uses in many fields that people pay more and more attention to them. However, for anionic micelles, there are fewer reports.Recently, we have been interested in the micellar growth induced by an increase in the amount of anionic surfactant, sodium dodecyl trioxyethylene sulfate (SDES), and salts, AlCl 3 , CaCl 2 , MgCl 2 , KBr, NaCl, etc. in systems where wormlike micelles or network structures are formed. In this work, rheological methods and freeze-fracture transmission electron microscopy (FF-TEM) were applied to investigate the effect of surfactant concentration on the formation and viscoelasticity of wormlike micelles and network structures in anionic surfactant SDES aqueous solutions in the presence of the multivalent counterion electrolyte AlCl 3 . Some interesting and noticeable conclusions will enrich the theory and application of wormlike micelles.Abstract Wormlike micelles and network structures were obtained for the samples with the anionic surfactant, sodium dodecyl trioxyethylene sulfate (SDES), and multivalent counterion electrolyte AlCl 3 fixed in a proper concentration according to rheological measurements and the technique of freeze-fracture transmission electron microscopy (FF-TEM). The characteristics of a non-Newtonian fluid and the phenomenon of shear-induced structures transition were acquired from the steady-shear experiments. The TEM micrographs show the coexistence of wormlike micelles, entangled network structures, rod-and sphere-like micelles in the solutions.The Cole-Cole plot shows the rheological behavior of the non-linear viscoelasticity, the departure from the Maxwell model, and a relaxation time that is not simple. The plateau modulus G 0 and the relaxation time s were also investigated to express the rheological properties of the wormlike micellar solutions.

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Section: Resultscontrasting

confidence: 44%

Effect of surfactant concentration on the formation and viscoelasticity of anionic wormlike micelle by the methods of rheology and freeze-fracture TEM

Wang

2002

Rheologica Acta

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“…It is the critical molar ratio of polar solvent to lecithin molecules at which maximum amount of external organic phase is entrapped, and thereafter the phase separation of the organogel accrue. 26,55,56 The n cr values can be easily determined with the help of rheological measurements or visual and optical observations of a ternary system between cross-polarizers. In most of the solvents employed in the preliminary studies on lecithin organogels, the n cr values were found to be in the range of 1 to 12 (as shown in Table 2) employing 80:16:04 weight percentages of lecithin, organic solvent, and water.…”

Section: Phase Behavior Of Organogelsmentioning

confidence: 99%

Lecithin organogels as a potential phospholipid-structured system for topical drug delivery: A review

2005

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The purpose of this review is to give an insight into the considerable potential of lecithin organogels (LOs) in the applications meant for topical drug delivery. LOs are clear, thermodynamically stable, viscoelastic, and biocompatible jelly-like phases, chiefly composed of hydrated phospholipids and appropriate organic liquid. These systems are currently of interest to the pharmaceutical scientist because of their structural and functional benefits. Several therapeutic agents have been formulated as LOs for their facilitated transport through topical route (for dermal or transdermal effect), with some very encouraging results. The improved topical drug delivery has mainly been attributed to the biphasic drug solubility, the desired drug partitioning, and the modification of skin barrier function by the organogel components. Being thermodynamically stable, LOs are prepared by spontaneous emulsification and therefore possess prolonged shelf life. The utility of this novel matrix as a topical vehicle has further increased owing to its very low skin irritancy potential. Varied aspects of LOs viz formation, composition, phase behavior, and characterization have been elaborated, including a general discussion on the developmental background. Besides a comprehensive update on the topical applications of lecithin organogels, the review also includes a detailed account on the mechanistics of organogelling.

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“…This kind of jelly like phases was exhaustively characterized in previous works. 15,17,18,30 The lecithin organogel at molar ratio n w ≈ 3, as followed from the scaling behavior, consists of branched polymer-like micelles. Values for the extrapolated scaling exponents are given in Table 1, together with values predicted by models for linear and branched micellar aggregates.…”

Section: Scaling Behaviormentioning

confidence: 99%

Lecithin Organogel with New Rheological and Scaling Behavior

et al. 2001

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It was established from an experimental study on a lecithin organogel in n-decane performed by means of an oscillatory rheology that frequency dependencies for complex viscosity and storage modulus have intermediate plateaus at certain molar ratios of water to lecithin. This type of rheological behavior was previously observed for blends of homopolymers which differ significantly in their molecular weight. To mathematically describe the experimental data, a Maxwell model including two relaxation processes (i.e., two elements in parallel) was considered. Both relaxation modes were constrained according to the known interrelation between terminal relaxation time, zero-shear viscosity, and plateau modulus. The experimental results were in good agreement with the model considered. By applying a fitting procedure, two sets of values for relaxation time, zero-shear viscosity and plateau modulus, were obtained for each of the relaxation processes. When the scaling behavior was examined, a disagreement with current models for the polymer-like micelles was found. The presented results lead to a suggestion that the lecithin organogel at increased water-to-lecithin molar ratios has more complicated structural organization than that observed for surfactant based micellar aggregates before.

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The Branching of Reversed Polymer-like Micelles of Lecithin by Sugar-Containing Surfactants

Cited by 16 publications

References 43 publications

Effect of surfactant concentration on the formation and viscoelasticity of anionic wormlike micelle by the methods of rheology and freeze-fracture TEM

Effect of surfactant concentration on the formation and viscoelasticity of anionic wormlike micelle by the methods of rheology and freeze-fracture TEM

Lecithin organogels as a potential phospholipid-structured system for topical drug delivery: A review

Lecithin Organogel with New Rheological and Scaling Behavior

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