Temperature dependence of the surfactant film bending elasticity in a bicontinuous sugar surfactant based microemulsion: a quasielastic scattering study

Wellert, Stefan; Karg, Matthias; Holderer, Olaf; Richardt, André; Hellweg, Thomas

doi:10.1039/c0cp02044c

Cited by 23 publications

(24 citation statements)

References 53 publications

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“…The possible treatment of diffusion as an additive term was discussed by Hellweg and coworkers [39,40]. The relative amplitudes must favor the undulations at high Q.…”

Section: Appendix A: Experimental Detailsmentioning

confidence: 99%

Acceleration of membrane dynamics adjacent to a wall

et al. 2012

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The dynamics of an induced lamellar microemulsion adjacent to a planar hydrophilic surface (45 ns) were found to be three times faster compared to the bicontinuous bulk structure (133 ns). For these investigations the grazing incidence technique for neutron spin echo spectroscopy has been developed to resolve the depth dependent near surface dynamics. The observation is rationalized in terms of membrane hydrodynamics, where the flow fields reflected by the surface lead to a crossover from classical to confined fluctuations, and faster dynamics on large length scales (also known as "lubrication") are predicted.

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“…The possible treatment of diffusion as an additive term was discussed by Hellweg and coworkers [39,40]. The relative amplitudes must favor the undulations at high Q.…”

Section: Appendix A: Experimental Detailsmentioning

confidence: 99%

Acceleration of membrane dynamics adjacent to a wall

et al. 2012

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“…As a somewhat more straightforward approach using an effective viscosity η eff = 3η instead of the macroscopic solvent viscosity to account for dissipation between the solvent and the membrane has proven to yield good results [20,23]. For monolayers surrounded by two different solvents (e.g., oil and water as in our case or in microemulsion sponge phases) the average of the two viscosities may be used instead of the solvent viscosity [24] to obtain more realistic values of κ. In any case, the dissipation of energy via the viscosity of the solvent(s) is an issue that will cause some uncertainty and even more so the dissipation of energy within the membrane/monolayer that typically is not considered at all.…”

Section: B Neutron Spin Echo (Nse)mentioning

confidence: 99%

Structure and dynamics of nanoemulsions: Insights from combining dynamic and static neutron scattering

Hoffmann

Heunemann

Farago³

et al. 2012

Phys. Rev. E

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Despite their lack of thermodynamical stability, nanoemulsions can show a remarkable degree of kinetic stability. Among the various different preparation methods the phase-inversion concentration method is particularly interesting as it occurs spontaneously. Here we investigate such a system composed of a surfactant, cosurfactant, and oil that upon dilution with water forms long time metastable oil-in-water nanoemulsion droplets. The dynamics of the amphiphilic monolayers and its elastic properties is important for their stability and therefore the monolayer dynamics have been investigated by neutron spin echo (NSE). Despite the difficulties arising from the inherently polydisperse nature and the large number of different components necessarily contained in commercial nanoemulsion formulations, information concerning the membrane rigidity was extracted from the combination of small angle neutron scattering and NSE and several different formulations are compared. These results show that small amounts of different admixed ionic surfactants can modify the monolayer rigidity substantially and similarly effects of surface bound polyelectrolytes have been evaluated.

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“…When comparing viscosities of microemulsions (in the range of 2-5cP [41]) and diffusion constants (in the range of 5 × 10 −8 cm 2 /s [42]) an effective particle radius of about 10-20 nm = 100-200 Å is reasonable indicating the diffusion of correlation volumes as described above. Interestingly [16], the diffusion effects can govern the viscosity measurements ( Fig.…”

Section: Discussionmentioning

confidence: 97%

Exploring Hidden Local Ordering in Microemulsions with a Weak Directive Second Order Parameter

2020

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So far, the near-surface ordering of microemulsions was focused on lamellar ordering while the bulk microemulsion was bicontinuous. In a series of different non-ionic surfactants the near-surface ordering of microemulsions at a hydrophilic silicon surface was studied using grazing incidence small angle neutron scattering. For the surfactant C 8 E 3 , most likely a gyroid structure was found at the solid-liquid interface, while the more efficient surfactants find lamellar ordering up to lamellar capillary condensation. The ranges for near-surface ordering are deeper than the bulk correlation lengths. These findings point towards theories that use directional order parameters that would lead to deeper near-surface ordering than simple theories with a single scalar order parameter would predict. Rheology experiments display high viscosities at very low shear rates and, therefore, support the existence of a directional order parameter.

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Temperature dependence of the surfactant film bending elasticity in a bicontinuous sugar surfactant based microemulsion: a quasielastic scattering study

Cited by 23 publications

References 53 publications

Acceleration of membrane dynamics adjacent to a wall

Acceleration of membrane dynamics adjacent to a wall

Structure and dynamics of nanoemulsions: Insights from combining dynamic and static neutron scattering

Exploring Hidden Local Ordering in Microemulsions with a Weak Directive Second Order Parameter

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