Solubilisation of different medium chain esters in zwitterionic surfactant solutions – Effects on phase behaviour and structure

Barth, Anina; Prévost, Sylvain; Popig, Jens; Dzionara, Michaela; Hedicke, Gabriele; Gradzielski, Michael

doi:10.1016/j.jcis.2011.06.082

Cited by 5 publications

(3 citation statements)

References 63 publications

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“…In the present investigation, as components for the formulation of a pharmaceutically acceptable system, − we have employed ethyl oleate (EO) as oil, Brij 96 as nonionic surfactant, and ethanol to hexanol as cosolvents or cosurfactants, where however after some general scans we concentrated on butanol as cosurfactant. Such longer-chain esters are challenging for the formulation of microemulsions, as it is well-known that for instance triglycerides are very difficult to be formulated in the form of microemulsions and the simple medium- and long-chain esters have more or less pronounced amphiphilic character . The characterization of these systems has been done by the combination of complementary methods like viscosity, surface tension, dynamic light scattering (DLS), small-angle neutron scattering (SANS), 1 H NMR rotating frame nuclear Overhauser effect spectroscopy (ROESY), and cyclic voltammetry.…”

Section: Introductionmentioning

confidence: 99%

Probing the Microstructure of Nonionic Microemulsions with Ethyl Oleate by Viscosity, ROESY, DLS, SANS, and Cyclic Voltammetry

et al. 2012

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Microemulsions are important formulations in cosmetics and pharmaceutics and one peculiarity lies in the so-called "phase inversion" that takes place at a given water-to-oil concentration ratio and where the average curvature of the surfactant film is zero. In that context, we investigated the structural transitions occurring in Brij 96-based microemulsions with the cosmetic oil ethyl oleate and studied the influence of the short chain alcohol butanol on their structure and properties as a function of water addition. The characterization has been carried out by means of transport properties, spectroscopy, DLS, SANS, and electrochemical methods. The results confirm that the nonionic Brij 96 in combination with butanol as cosurfactant forms a U-type microemulsion that upon addition of water undergoes a continuous transition from swollen reverse micelles to oil-in-water (O/W) microemulsion via a bicontinuous region. After determining the structural transition through viscosity and surface tension, the 2D-ROESY studies give an insight into the microstructure, i.e., the oil component ethyl oleate mainly is located at the hydrophobic tails of surfactant while butanol molecules reside preferentially in the interface. SANS experiments show a continuous increase of the size of the structural units with increasing water content. The DLS results are more complex and show the presence of two relaxation modes in these microemulsions for low water content and a single diffusive mode only for the O/W microemulsion droplets. The fast relaxation reflects the size of the structural units while the slower one is attributed to the formation of a network of percolated microemulsion aggregates. Electrochemical studies using ferrocene have been carried out and successfully elucidated the structural transformations with the help of diffusion coefficients. An unusual behavior of ferrocene has been observed in the present microheterogeneous medium, giving a deeper insight into ferrocene electrochemistry. NMR-ROESY experiments give information regarding the internal organization of the microemulsion droplets. In general, one finds a continuous structural transition from a W/O over a bicontinuous to an O/W microemulsion, however with a peculiar network formation over an extended concentration range, which is attributed to the somewhat amphiphilic oil ethyl oleate. The detailed knowledge of the structural behavior of this type of system might be important for their future applications.

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Section: Introductionmentioning

confidence: 99%

Probing the Microstructure of Nonionic Microemulsions with Ethyl Oleate by Viscosity, ROESY, DLS, SANS, and Cyclic Voltammetry

et al. 2012

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“…Medium-chain alcohols from bio-oil could insert themselves between surfactant molecules acting as cosurfactant. Consequently, a mixed interfacial film could formulate which was easy to bend . Part of the esters such as ethyl oleate were found to locate at the surfactant tails .…”

Section: Resultsmentioning

confidence: 99%

“…Consequently, a mixed interfacial film could formulate which was easy to bend. 54 Part of the esters such as ethyl oleate were found to locate at the surfactant tails. 55 Likewise, MEs could be entangled in the palisade layer with the hydrophobic chain intertwining with surfactant tails (Figure 6b).…”

Section: Solubilization Mechanismmentioning

confidence: 99%

Upgrading Sewage Sludge Liquefaction Bio-Oil by Microemulsification: The Effect of Ethanol as Polar Phase on Solubilization Performance and Fuel Properties

et al. 2017

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Sewage sludge liquefaction bio-oil is capturing extensive attention for its sustainability and easy availability. However, some limitations of bio-oil such as high viscosity and poor cold flow properties hamper its direct application in engines. Two microemulsions including ethanol-in-diesel (M1) and diesel microemulsion (M2) were produced to upgrade bio-oil. Adding ethanol in M1 facilitated bio-oil solubilization and improved fuel properties of bio-oil. Because of low viscosity and low pour point of ethanol, M1 with ethanol as polar phase produced a more promising biofuel with acceptable viscosity and better cold flow properties compared with M2. Through microemulsification in diesel, hydrophilic and hydrophobic bio-oil components may penetrate into the polar core and the continuous phase, respectively, while amphiphilic components mainly located at the interface. The hydrogen bonding between ethanol and hydrophilic bio-oil components could enhance solubility and improve stability. Besides, polar phase ethanol could also act as a solvent to dissolve more less-hydrophilic bio-oil components into the polar core.

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Thermodynamic properties of micellization of Sulfobetaine-type Zwitterionic Gemini Surfactants in aqueous solutions – A free energy perturbation study

Liu

et al. 2012

Journal of Colloid and Interface Science

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Solubilisation of different medium chain esters in zwitterionic surfactant solutions – Effects on phase behaviour and structure

Cited by 5 publications

References 63 publications

Probing the Microstructure of Nonionic Microemulsions with Ethyl Oleate by Viscosity, ROESY, DLS, SANS, and Cyclic Voltammetry

Probing the Microstructure of Nonionic Microemulsions with Ethyl Oleate by Viscosity, ROESY, DLS, SANS, and Cyclic Voltammetry

Upgrading Sewage Sludge Liquefaction Bio-Oil by Microemulsification: The Effect of Ethanol as Polar Phase on Solubilization Performance and Fuel Properties

Thermodynamic properties of micellization of Sulfobetaine-type Zwitterionic Gemini Surfactants in aqueous solutions – A free energy perturbation study

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