Temperature dependent cubic and hexagonal close packing in micellar structures

Wolff, Nicole; Gerth, Stefan; Gutfreund, Philipp; Wolff, Max

doi:10.1039/c4sm01569j

Cited by 8 publications

(8 citation statements)

References 29 publications

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“…This is a severe challenge for samples with strong SAS, when the SAS can be equal or stronger than the specular signal. Figure 5, right panel, demonstrates this effect [20]. The detected specular NR is plotted on a logarithmic scale versus Q z (circles marked with a cross).…”

Section: Off-specular and Gisansmentioning

confidence: 76%

“…In addition the texture of the self assembly [11] as well as the reconstruction of the structure after the cession of shear [45] strongly depends on the surface energy of the solid substrate. For micellar solutions showing a phase transition from cubic to hexagonal ordering a hysteresis in the transition temperature has been reported [20,43,44]. Some neutron reflectometers offer the possibility to measure from horizontal samples and liquid surfaces.…”

Section: Examplesmentioning

confidence: 99%

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Grazing incidence scattering

Wolff

2018

EPJ Web of Conferences

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Reflectometry experiments probe the scattering length density along the normal of interfaces by analysing the specularly scattered intensity. Lateral fluctuations result in intensity scattered away from the specular condition. In this paper the principles and peculiarities of grazing incidence scattering experiments are explained. One specific example, the self assembly of polymer micelles close to interfaces, is taken as a show case in order to introduce the scattering geometry and accessible length scales. The basic idea of the distorted wave Born approximation is lined out and some scientific examples are summarized.

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Section: Off-specular and Gisansmentioning

confidence: 76%

Section: Examplesmentioning

confidence: 99%

Grazing incidence scattering

Wolff

2018

EPJ Web of Conferences

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“…Epitaxy near a planar surface is leading to very diverse structures [36][37][38][39] ranging from lamellar over hexagonal to cubic structures. Unfavorable suppression of Bragg peaks in the lateral dimension can be very weak due to orientational averaging or random orientation although the lateral correlation lengths may be very large.…”

Section: Discussionmentioning

confidence: 99%

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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“…In aqueous solutions, these molecules tend to form micelles. Pluronic F 127 18.5 wt% in heavy water offers a very rich scattering behaviour, is used in many applications and serves as a model micellar solution (Dumortier et al, 2006;Wolff et al, 2014;Huang et al, 1998;Wanka et al, 1994).…”

Section: Merged Data Of a Tof Reflectometermentioning

confidence: 99%

Överlåtaren: a fast way to transfer and orthogonalize two-dimensional off-specular reflectivity data

et al. 2016

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Reflectivity measurements offer unique opportunities for the study of surfaces and interfaces, and specular reflectometry has become a standard tool in materials science to resolve structures normal to the surface of a thin film. Off‐specular scattering, which probes lateral structures, is more difficult to analyse, because the Fourier space being probed is highly anisotropic and the scattering pattern is truncated by the interface. As a result, scattering patterns collected with (especially time‐of‐flight) neutron reflectometers are difficult to transform into reciprocal space for comparison with model calculations. A program package is presented for a generic two‐dimensional transformation of reflectometry data into q space and back. The data are represented on an orthogonal grid, allowing cuts along directions relevant for theoretical modelling. This treatment includes background subtraction as well as a full characterization of the resolution function. The method is optimized for computational performance using repeatable operations and standardized instrument settings.

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Temperature dependent cubic and hexagonal close packing in micellar structures

Cited by 8 publications

References 29 publications

Grazing incidence scattering

Grazing incidence scattering

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

Överlåtaren: a fast way to transfer and orthogonalize two-dimensional off-specular reflectivity data

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