Small-Angle Neutron Scattering from Diffuse Interfaces. 2. Polydisperse Shells in Water-n-Alkane-C10E4 Microemulsions

Gradzielski, Michael; Langévin, D.; Magid, L. J.; Strey, R.

doi:10.1021/j100035a030

Cited by 63 publications

(77 citation statements)

References 19 publications

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“…The real scattering length density distribution of a bilayer membrane, however, is expected to be more complex than a sharp interface [16]. This explains the overestimation of the scattering intensity in the high Q range as seen in Figure 3, as such a diffuse interface leads to a sharper decrease of the scattering intensity [17].…”

Section: Mixture Of Emulsifier and Water (Sample #1)mentioning

confidence: 97%

Structural Analysis of a Modern o/w-Emulsion Stabilized by a Polyglycerol Ester Emulsifier and Consistency Enhancers

Dahl

Friedrich

Juergen

et al. 2018

Colloids and Interfaces

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Abstract:The aim of our work was to study the structure of a typical modern cosmetic oil-in-water emulsion (o/w-emulsion), based on the emulsifier polyglyceryl-3 dicitrate/stearate and glycerylstearate/stearyl alcohol as consistency enhancer. We have used a systematic approach building up the cosmetic emulsion step by step, characterizing all systems by using Small Angle Neutron Scattering (SANS), Differential Scanning Calorimetry (DSC), Freeze Fracture Transmission Electron Microscopy (FF-TEM), light microscopy and rheology. The starting point was the pure emulsifier in water, which was shown to form lamellar stacked bilayers with a spacing of 7 nm, coexisting with polydisperse unilamellar vesicles in the sub-µm range. Upon addition of consistency enhancer, also multilamellar vesicles could be obtained. Then, oil has been added stepwise, until finally a complete cosmetic o/w-emulsion was obtained. In the final emulsion, oil droplets with sizes in the µm range are surrounded by multiple, irregularly spaced bilayer structures and vesicles. Approximately 30% of the water present in the system shows a restricted mobility ("encapsulated water") according to PFG-NMR. Crucial for the viscosity build-up is the presence of the oil droplets; a cream-like consistency is obtained by steric interaction of oil droplets and crystalline bilayer structures in the aqueous phase of the emulsion.

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Section: Mixture Of Emulsifier and Water (Sample #1)mentioning

confidence: 97%

Structural Analysis of a Modern o/w-Emulsion Stabilized by a Polyglycerol Ester Emulsifier and Consistency Enhancers

Dahl

Friedrich

Juergen

et al. 2018

Colloids and Interfaces

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“…The position of this minimum, which is followed by a small maximum, is related to the radius of the shells according to q ∼ π/R 0 . At large values of q, the intensity decreases with an exp(−q 2 t 2 )·q −2 dependence as a result of the diffuse nature of the amphiphilic film with an interface thickness t. 31 We described the experimental data using the form factor for polydisperse spherical Gaussian shells with diffuse interface and additional coherent scattering from the droplet core, as derived by Foster et al 32 To account for excluded volume interactions, we applied the structure factor of hard spheres with surface adhesion (sticky hard spheres). 33,34 The resulting curve is plotted in Figure 5.…”

Section: Characterizationmentioning

confidence: 98%

Soret Coefficient in Nonionic Microemulsions: Concentration and Structure Dependence

et al. 2013

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Here we investigate the thermal diffusion behavior of the nonionic microemulsion water/n-decane/pentaethylene glycol monododecyl ether (C12E5). We study the dependence of the Soret coefficient on the structure and composition by infrared thermal diffusion Rayleigh scattering. The form and size of the microemulsion structure is characterized by dynamic light scattering and small angle neutron scattering. The system was examined in the one-phase region between the emulsification failure boundary and the near critical boundary, where oil swollen nanostructures stabilized by an amphiphilic surfactant film are dispersed in a continuous water phase. The size and shape of these structures as well as the interfacial properties of microemulsions can be varied by changing temperature and composition, which allows a systematic study of their influence on the thermal diffusion properties. In addition, we analyze the relationship between the Soret coefficient and the temperature dependence of the interfacial tension as proposed by A. Parola and R. Piazza (Eur. Phys. J. E 2004, 15, 255-263) and find reasonable agreement for spherical microemulsion droplets.

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“…37,38 For a more precise description one has to include this effect. Assuming the scattering length density profile to change smoothly across the interface Strey et al 37 took this effect into account by convolution of the usual step-profile in the scattering length density with a Gaussian of standard deviation t. In effect it amounts to multiplying the right-hand side of Eq.…”

Section: Diffuse Profilesmentioning

confidence: 99%

A small-angle neutron scattering study of nonionic surfactant molecules at the water–oil interface: Area per molecule, microemulsion domain size, and rigidity

Sottmann

Strey

Chen

1997

The Journal of Chemical Physics

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182

212

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The small-angle neutron scattering (SANS) of bicontinuous microemulsions of 19 different water-n-alkane-CiEj (n-alkylpolyglycolether) systems has been measured. All scattering curves exhibit a broad scattering peak which permits determining the characteristic length scale ξ for bicontinuous structures at symmetric water and oil volume fractions, i.e., φ=0.5. Various random models predict ξ=aδφ(1−φ)/φc. We find that ξ is indeed inversely proportional to the surfactant volume fraction φc. Approximating the effective surfactant chain length δ by δ=νc/ac, where ac and νc are the area and the volume of the surfactant molecule, the numerical value for a is determined to be a=7.16, which is close to, but significantly different from those used in theoretical models. The head group area ac at the water–oil interface is obtained from the large q part of the scattering curves. It is found to be independent of i and k, the carbon numbers of the alkyl chain of the surfactant and of the alkane, respectively. However, it depends strongly, and nearly linearly, on the head group size j of the surfactant. Within experimental error it is described by ac=29.3+6.20j (Å2).

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Small-Angle Neutron Scattering from Diffuse Interfaces. 2. Polydisperse Shells in Water-n-Alkane-C10E4 Microemulsions

Cited by 63 publications

References 19 publications

Structural Analysis of a Modern o/w-Emulsion Stabilized by a Polyglycerol Ester Emulsifier and Consistency Enhancers

Structural Analysis of a Modern o/w-Emulsion Stabilized by a Polyglycerol Ester Emulsifier and Consistency Enhancers

Soret Coefficient in Nonionic Microemulsions: Concentration and Structure Dependence

A small-angle neutron scattering study of nonionic surfactant molecules at the water–oil interface: Area per molecule, microemulsion domain size, and rigidity

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