Influence of a perfluorohexane-enriched atmosphere on the viscoelasticity and structural order of self-assembled nanodomains of semifluorinated alkanes at the air/water interface - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue ChemPhysChem Année : 2019

Influence of a perfluorohexane-enriched atmosphere on the viscoelasticity and structural order of self-assembled nanodomains of semifluorinated alkanes at the air/water interface

Salomé Mielke
  • Fonction : Auteur
Wasim Abuillan
  • Fonction : Auteur
Mariam Veschgini
  • Fonction : Auteur
Xianhe Liu
  • Fonction : Auteur
Oleg Konovalov
Marie Pierre Krafft
Motomu Tanaka
  • Fonction : Auteur
  • PersonId : 1082286

Résumé

Semifluorinated alkanes are promising candidates to stabilize microbubbles enriched with a fluorocarbon gas for sonographic imaging, since they form highly uniform, mesoscopic domains with the diameter of several tens of nm by self-assembly at the air/water interface. In this study, we investigated how an atmosphere enriched with a fluorocarbon gas (perfluorohexane) influences the interfacial viscoelasticity and structural order of semifluorinated alkane domains by the combination of dilational rheology and grazing incidence small-angle Xray scattering (GISAXS) at the air/water interface. The elastic modulus of semifluorinated alkane monolayers was several times larger compared to those of surfactants with hydrocarbon segments, which can be attributed to strong dipole repulsions originating from the CF 3 termini and CF 2-CH 2 junction. The presence of perfluorohexane in the atmosphere led to a distinct decrease in the elasticity, which can be correlated to an increase in the lateral compressibility observed by pressure-area isotherms. The interfacial viscosity of semifluorinated alkane monolayers calculated from the Kelvin-Voigt model was by two orders of magnitude lower than those of surfactants with hydrocarbon segments due to the much weaker cohesion between the fluorocarbon segments. We analyzed GISAXS results by the full calculation of structure and form factors, and found that the hemispherical, about 30 nm large domains of semifluorinated alkanes form hexagonal lattices both in air and in the atmosphere enriched with perfluorohexane. Intriguingly, the presence of perfluorohexane barely influences the domain size or the distance between neighboring domains, indicating that perfluorohexane molecules do not intercalate into the fluorocarbon regions of the domains but adsorb weakly to the free spaces between the domains. Thus, the combination of dilational rheology and quantitative GISAXS is straightforward for the optimization of membrane, bubble, and emulsion systems by fine-tuning of molecular structures. These studies demonstrate the sturdiness of the self-assembled semifluorinated alkane domains that can retain the structural integrity in the presence of fluorocarbon gas.
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Dates et versions

hal-03018497 , version 1 (22-11-2020)

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Salomé Mielke, Wasim Abuillan, Mariam Veschgini, Xianhe Liu, Oleg Konovalov, et al.. Influence of a perfluorohexane-enriched atmosphere on the viscoelasticity and structural order of self-assembled nanodomains of semifluorinated alkanes at the air/water interface. ChemPhysChem, 2019, ⟨10.1002/cphc.201900316⟩. ⟨hal-03018497⟩
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