Braun, Larissa ; Hohenschutz, Max ; Diat, Olivier ; Klitzing, Regine von ; Bauduin, Pierre (2023)
Repulsive, but sticky - Insights into the non-ionic foam stabilization mechanism by superchaotropic nano-ions.
In: Journal of Colloid and Interface Science, 641
doi: 10.1016/j.jcis.2023.03.030
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
Hypothesis The superchaotropic Keggin polyoxometalate α-SiW12O404− (SiW) was recently shown to stabilize non-ionic surfactant (C18:1E10) foams owing to electrostatic repulsion that arises from the adsorption of SiW-ions to the foam interfaces. The precise mechanism of foam stabilization by SiW however remained unsolved.
Experiments Imaging and conductimetry were used on macroscopic foams to monitor the foam collapse under free drainage and small angle neutron scattering (SANS) at a given foam height allowed for the tracking of the evolution of film thickness under quasi-stationary conditions. Thin film pressure balance (TFPB) measurements enabled to quantify the resistance of single foam films to external pressure and to identify intra-film forces.
Findings At low SiW/surfactant ratios, the adsorption of SiW induces electrostatic repulsion within foam films. Above a concentration threshold corresponding to an adsorption saturation, excess of SiW screens the electrostatic repulsion that leads to thinner foam films. Despite screened electrostatics, the foam and single foam films remain very stable caused by an additional steric stabilizing force consistent with the presence of trapped micelles inside the foam films that bridge between the interfaces. These trapped micelles can serve as a surfactant reservoir, which promotes self-healing of the interface leading to much more resilient foam films in comparison to bare surfactant foams/films.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2023 |
| Autor(en): | Braun, Larissa ; Hohenschutz, Max ; Diat, Olivier ; Klitzing, Regine von ; Bauduin, Pierre |
| Art des Eintrags: | Bibliographie |
| Titel: | Repulsive, but sticky - Insights into the non-ionic foam stabilization mechanism by superchaotropic nano-ions |
| Sprache: | Englisch |
| Publikationsjahr: | Juli 2023 |
| Verlag: | Elsevier |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Journal of Colloid and Interface Science |
| Jahrgang/Volume einer Zeitschrift: | 641 |
| DOI: | 10.1016/j.jcis.2023.03.030 |
| Kurzbeschreibung (Abstract): | Hypothesis The superchaotropic Keggin polyoxometalate α-SiW12O404− (SiW) was recently shown to stabilize non-ionic surfactant (C18:1E10) foams owing to electrostatic repulsion that arises from the adsorption of SiW-ions to the foam interfaces. The precise mechanism of foam stabilization by SiW however remained unsolved. Experiments Imaging and conductimetry were used on macroscopic foams to monitor the foam collapse under free drainage and small angle neutron scattering (SANS) at a given foam height allowed for the tracking of the evolution of film thickness under quasi-stationary conditions. Thin film pressure balance (TFPB) measurements enabled to quantify the resistance of single foam films to external pressure and to identify intra-film forces. Findings At low SiW/surfactant ratios, the adsorption of SiW induces electrostatic repulsion within foam films. Above a concentration threshold corresponding to an adsorption saturation, excess of SiW screens the electrostatic repulsion that leads to thinner foam films. Despite screened electrostatics, the foam and single foam films remain very stable caused by an additional steric stabilizing force consistent with the presence of trapped micelles inside the foam films that bridge between the interfaces. These trapped micelles can serve as a surfactant reservoir, which promotes self-healing of the interface leading to much more resilient foam films in comparison to bare surfactant foams/films. |
| Fachbereich(e)/-gebiet(e): | 05 Fachbereich Physik 05 Fachbereich Physik > Institut für Festkörperphysik (2021 umbenannt in Institut für Physik Kondensierter Materie (IPKM)) |
| Hinterlegungsdatum: | 04 Mai 2023 08:16 |
| Letzte Änderung: | 04 Mai 2023 08:16 |
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