Characterization of the micelle structure of oleic acid-based gemini surfactants: effect of stereochemistry

Abstract

In this study, we synthesize a novel oleic acid-based gemini surfactant with carboxylate headgroups, and study the effect of stereochemistry (anti- vs. syn-) on self-aggregation properties in water. We investigate these properties using phase diagrams, static surface tension, and one-dimensional and two-dimensional nuclear magnetic resonance (NMR) measurements. We find that a phase transition from a hexagonal liquid crystal (H1) phase to a lamellar liquid crystal (Lα) phase occurs at a lower surfactant concentration in the syn form, when compared with the anti form. In addition, the syn form gemini surfactant forms micelles with a close packing of the headgroups via hydrogen bonding. This was supported by static surface tensiometry; the area occupied by surfactant molecules at the air/aqueous solution interface is smaller for the syn form than for the anti form. We propose that, for the syn form gemini surfactant, the closer packing of the headgroups as well as the hydrogen bonding network around the micelle interface prevent water penetration into the hydrophobic part of the micelle.

Renewable dissymmetric sulfonate gemini surfactants from addition of sodium hydrogensulfite to alkyl linoleate

“…Concerning Γ max and A min values of the three gemini surfactants, it is interesting to note that SELD gave the slightly higher Γ max value and lower A min value when compared with SBLD, suggesting a more densely packing of SELD at the water‐air interface. This may be caused by a different composition of the regioisomers for the synthesized sulfonate gemini surfactants (Figure S2), which is similar in accordance with previous literature focusing on the effect of stereochemistry of gemini surfactants on their interfacial properties and self‐aggregation properties in water 29 . Further evidence from extensive experimental studies is required to verify this.…”

“…This may be caused by a different composition of the regioisomers for the synthesized sulfonate gemini surfactants (Figure S2), which is similar in accordance with previous literature focusing on the effect of stereochemistry of gemini surfactants on their interfacial properties and self-aggregation properties in water. 29 Further evidence from extensive experimental studies is required to verify this. As is shown in Table 3, we also note that the calculated ΔG 0 ads values of the synthesized sulfonate gemini surfactants are always negatively larger than the corresponding ΔG 0 mic values, indicating that the adsorption occurs predominantly over the micellization that is seen in aqueous solution.…”

“…Natural long-chain unsaturated fatty acids, such as oleic acid, linoleic acid, and erucic acid, are deemed to be some of the renewable platform molecules for surfactants production owing to their carbon-neutrality and potential as alternatives to petrochemicals. 26,27 Oleic acid-based gemini or heterogemini surfactants with different headgroups, such as dissymmetric heterogemini surfactants containing a phosphate group and a hydroxyl group, 25 dissymmetric heterogemini surfactants with a sulfonate group and a hydroxyl group, 28 anionic gemini surfactants with carboxylic acid headgroups, 20,21,29 cationic gemini surfactants containing a quaternary ammonium group and a hydroxyl group, 30 have been designed and developed by the research group of Sakai and Abe. 31 Despite the great progress that has been achieved, the commercial production and availability of gemini surfactants is still limited due to the complicated synthesis and problematic purification.…”

Structural Change of an α-Gel (α-Form Hydrated Crystal) Induced by Temperature and Shear Flow in an Oleic Acid Based Gemini Surfactant System

“…We have already studied the interfacial properties and self-aggregation structures of a carboxylate-type gemini surfactant synthesized from oleic acid ( anti -CC-9,9-EsH10-Na, Figure ). − We found that this surfactant showed excellent interfacial activity and solubility in water, − as generally observed in gemini surfactant systems. − Additionally, this surfactant yielded highly ordered α-gels in the presence of 1-tetradecanol (C 14 OH) even at high water concentrations . In this work, we studied the structural changes in the α-gel bilayers and domains induced by temperature and shear flow in the anti -CC-9,9-EsH10-Na/C 14 OH/water system.…”

Cancer Nanomedicine: A New Era of Successful Targeted Therapy

“…Micelles functionally facilitate the absorption of water-insoluble fat and fat-soluble vitamins [80]. Their size is normally within in a range between 5 and 100 nm; amphiphilic molecules consist of a core: hydrophobic fragments and shell and hydrophilic moieties [81]. Water-insoluble drugs are usually intravenously administrated with an adjuvant solubilizing agent such as ethanol, which mainly has common toxic side effects [82].…”