A complete characterization of the structure of the vesicular phase in AOT — Brine system in the diluted region of the phase diagram

Wolanin, Julie; Barré, Loı̈c; Dalmazzone, Christine; Bauer, Daniela

doi:10.1016/j.colsurfa.2018.09.052

Cited by 6 publications

(11 citation statements)

References 39 publications

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“…Bilayer B2 has the same dimension as the bilayer of bulk vesicles characterized by small-angle X-ray scattering experiments. 68 Moreover, both bilayers (B1 and B2) have the same water volume fraction. The total thickness of the adsorbed layer (9.2 nm) is smaller than the vesicle diameter (14 nm) characterized with DLS measurements, 68 suggesting the flattening of vesicles at the surface.…”

Section: ■ Resultsmentioning

confidence: 99%

“…68 Moreover, both bilayers (B1 and B2) have the same water volume fraction. The total thickness of the adsorbed layer (9.2 nm) is smaller than the vesicle diameter (14 nm) characterized with DLS measurements, 68 suggesting the flattening of vesicles at the surface. Thus, at intermediate pH, we assumed the formation of a layer composed of flattened vesicles, consistent with QCM-D estimations (8.5 nm found with the Kelvin−Voigt model).…”

Section: ■ Resultsmentioning

confidence: 99%

“…Details on the multiscale vesicle's characterization of the solution can be found in the litterature. 68 According to Iler et al, 69 the silica surface has amphoteric hydroxyl sites, and its point of zero charge (PZC) is supposed to be close to 2. The pH values for this study were chosen as a function of this PZC.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…Bilayer B2 has the same dimension as the bilayer of bulk vesicles characterized by SAXS experiments 68 . Moreover, both bilayers (B1 and B2) have the same water volume fraction.…”

Section: Intermediate Conditions: Ph ~6mentioning

confidence: 96%

“…Above the CVC (CVC=0.09 g/L=0.2 mmol/dm 3 ), the AOT/brine solution was mainly composed of small unilamellar vesicles (14 nm diameter) with a bilayer thickness of 2.7 nm. Details on the multiscale vesicle's characterization of the solution can be found in the litterature 68 .…”

Section: C20h37nao7smentioning

confidence: 99%

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Insight into Kinetics and Mechanisms of AOT Vesicle Adsorption on Silica in Unfavorable Conditions

et al. 2020

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The structure of adsorbed surfactant layers at equilibrium state has already been investigated using various experimental techniques. However, the comprehension of the formation of structural intermediates in non-equilibrium states and the resulting adsorption kinetics still remains a challenging task. The temporal characterization of these intermediate structures provides further understanding of the layer structure at equilibrium and of the main interactions involved in the adsorption process. In this article, we studied adsorption kinetics of AOT vesicles on silica at different pH at ambient temperature. AOT vesicles were formed in a brine solution. Quartz crystal microbalance with dissipation monitoring (QCM-D) was used to obtain information on the kinetics of surfactant adsorption and on the structure of the adsorbed layer at the equilibrium state.Additionally, neutron reflectivity experiments were performed to provide a detailed description of the mean surfactant concentration profile normal to the surface at equilibrium. Results suggest that vesicles in the bulk influence the adsorption mechanisms. In acidic conditions, after a time dependent structural rearrangement step followed by the rupture of initially adsorbed vesicles, the formation of a bilayer was observed. At intermediate and basic pH, in spite of the electrostatic repulsion between the negatively charged surfactants and silica, results demonstrated the existence of an adsorbed layer composed of AOT vesicles. Vesicles are more or less closely packed depending on the pH of the solution. Results show non-negligible influence of NaCl addition at pH values where adsorption is initially inhibited. Vesicle adsorption at intermediate and basic pH is probably due to the combination of attractive van der Waals interactions promoted in high ionic strength systems and the formation of hydrogen bonds. Interpretation of adsorption kinetics gave insight into adsorption mechanisms in an electrostatic repulsion environment.

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Section: ■ Resultsmentioning

confidence: 99%

Section: ■ Resultsmentioning

confidence: 99%

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…Bilayer B2 has the same dimension as the bilayer of bulk vesicles characterized by SAXS experiments 68 . Moreover, both bilayers (B1 and B2) have the same water volume fraction.…”

Section: Intermediate Conditions: Ph ~6mentioning

confidence: 96%

Section: C20h37nao7smentioning

confidence: 99%

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