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Shape and Structure Formation of Mixed Nonionic−Anionic Surfactant Micelles

Ludwig, Michael ; Geisler, Ramsia ; Prévost, Sylvain ; Klitzing, Regine von (2023)
Shape and Structure Formation of Mixed Nonionic−Anionic Surfactant Micelles.
In: Molecules, 2021, 26 (14)
doi: 10.26083/tuprints-00019619
Article, Secondary publication, Publisher's Version

Copyright Information: CC BY 4.0 International - Creative Commons, Attribution.

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Item Type: Article
Type of entry: Secondary publication
Title: Shape and Structure Formation of Mixed Nonionic−Anionic Surfactant Micelles
Language: English
Date: 14 November 2023
Place of Publication: Darmstadt
Year of primary publication: 2021
Place of primary publication: Basel
Publisher: MDPI
Journal or Publication Title: Molecules
Volume of the journal: 26
Issue Number: 14
Collation: 23 Seiten
DOI: 10.26083/tuprints-00019619
Corresponding Links:
Origin: Secondary publication DeepGreen

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.

Uncontrolled Keywords: small-angle neutron scattering, surfactant, micelles, mixed micelles, Tween20, polysorbate 20, BrijL23, Brij 35, SDS
Status: Publisher's Version
URN: urn:nbn:de:tuda-tuprints-196191
Additional Information:

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

Classification DDC: 500 Science and mathematics > 530 Physics
Divisions: 05 Department of Physics > Institute for Condensed Matter Physics > Soft Matter at Interfaces (SMI)
Date Deposited: 14 Nov 2023 14:02
Last Modified: 17 Nov 2023 10:22
SWORD Depositor: Deep Green
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/19619
PPN: 513264019
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