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Shape and Structure Formation of Mixed Nonionic–Anionic Surfactant Micelles

Ludwig, Michael ; Geisler, Ramsia ; Prévost, Sylvain ; Klitzing, R. von (2021)
Shape and Structure Formation of Mixed Nonionic–Anionic Surfactant Micelles.
In: Molecules, 26 (14)
doi: 10.3390/molecules26144136
Artikel, Bibliographie

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Kurzbeschreibung (Abstract)

Aqueous solutions of a nonionic surfactant (either Tween20 or BrijL23) and an anionic surfactant (sodium dodecyl sulfate, SDS) are investigated, using small-angle neutron scattering (SANS). SANS spectra are analysed by using a core-shell model to describe the form factor of self-assembled surfactant micelles; the intermicellar interactions are modelled by using a hard-sphere Percus–Yevick (HS-PY) or a rescaled mean spherical approximation (RMSA) structure factor. Choosing these specific nonionic surfactants allows for comparison of the effect of branched (Tween20) and linear (BrijL23) surfactant headgroups, both constituted of poly-ethylene oxide (PEO) groups. The nonionic–anionic surfactant mixtures are studied at various concentrations up to highly concentrated samples (Φ ≲ 0.45) and various mixing ratios, from pure nonionic to pure anionic surfactant solutions. The scattering data reveal the formation of mixed micelles already at concentrations below the critical micelle concentration of SDS. At higher volume fractions, excluded volume effects dominate the intermicellar structuring, even for charged micelles. In consequence, at high volume fractions, the intermicellar structuring is the same for charged and uncharged micelles. At all mixing ratios, almost spherical mixed micelles form. This offers the opportunity to create a system of colloidal particles with a variable surface charge. This excludes only roughly equimolar mixing ratios (X≈ 0.4–0.6) at which the micelles significantly increase in size and ellipticity due to specific sulfate–EO interactions.

Typ des Eintrags: Artikel
Erschienen: 2021
Autor(en): Ludwig, Michael ; Geisler, Ramsia ; Prévost, Sylvain ; Klitzing, R. von
Art des Eintrags: Bibliographie
Titel: Shape and Structure Formation of Mixed Nonionic–Anionic Surfactant Micelles
Sprache: Englisch
Publikationsjahr: 2021
Verlag: Molecular Diversity Preservation International (MDPI)
Titel der Zeitschrift, Zeitung oder Schriftenreihe: Molecules
Jahrgang/Volume einer Zeitschrift: 26
(Heft-)Nummer: 14
Kollation: 23 Seiten
DOI: 10.3390/molecules26144136
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Kurzbeschreibung (Abstract):

Aqueous solutions of a nonionic surfactant (either Tween20 or BrijL23) and an anionic surfactant (sodium dodecyl sulfate, SDS) are investigated, using small-angle neutron scattering (SANS). SANS spectra are analysed by using a core-shell model to describe the form factor of self-assembled surfactant micelles; the intermicellar interactions are modelled by using a hard-sphere Percus–Yevick (HS-PY) or a rescaled mean spherical approximation (RMSA) structure factor. Choosing these specific nonionic surfactants allows for comparison of the effect of branched (Tween20) and linear (BrijL23) surfactant headgroups, both constituted of poly-ethylene oxide (PEO) groups. The nonionic–anionic surfactant mixtures are studied at various concentrations up to highly concentrated samples (Φ ≲ 0.45) and various mixing ratios, from pure nonionic to pure anionic surfactant solutions. The scattering data reveal the formation of mixed micelles already at concentrations below the critical micelle concentration of SDS. At higher volume fractions, excluded volume effects dominate the intermicellar structuring, even for charged micelles. In consequence, at high volume fractions, the intermicellar structuring is the same for charged and uncharged micelles. At all mixing ratios, almost spherical mixed micelles form. This offers the opportunity to create a system of colloidal particles with a variable surface charge. This excludes only roughly equimolar mixing ratios (X≈ 0.4–0.6) at which the micelles significantly increase in size and ellipticity due to specific sulfate–EO interactions.

Freie Schlagworte: small-angle neutron scattering, surfactant, micelles, mixed micelles, Tween20, polysorbate 20, BrijL23, Brij 35, SDS
Zusätzliche Informationen:

This article belongs to the Special Issue Functional Colloids for Advanced Nanomaterials and Composites: From Theory to Applications

Fachbereich(e)/-gebiet(e): 05 Fachbereich Physik
05 Fachbereich Physik > Institut für Festkörperphysik (2021 umbenannt in Institut für Physik Kondensierter Materie (IPKM))
Hinterlegungsdatum: 06 Sep 2021 10:06
Letzte Änderung: 19 Jul 2024 10:07
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