Dokument: Phasenverhalten von Biotensiden
| Titel: | Phasenverhalten von Biotensiden | |||||||
| Weiterer Titel: | Phase behavior of biosurfactants | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=71047 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20251028-125023-6 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Birnbach, Janine [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Karg, Mathias [Gutachter] Prof. Dr. Delaittre, Guillaume [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 540 Chemie | |||||||
| Beschreibung: | Biosurfactants are produced by microorganisms from renewable resources and have complex
structural formulae. These complex structures result in unknown physico-chemical properties, knowledge of which is essential for the formulation of biosurfactants into industrial products. As these products usually contain several different components, biosurfactants have been studied in mixtures with other surfactants in this thesis. This investigation was conducted in pseudo-binary, ternary and quaternary systems with other surfactants and oil, in order to establish a structure-property relationship. The two most abundant biosurfactants, rhamnolipid and sophorolipid, were combined with cationic and nonionic model surfactants, respectively. Their self-assembled structures in water were analyzed with pulsed field-gradient spin-echo nuclear magnetic resonance spectroscopy (PGSE-NMR), small-angle X-ray (SAXS) and neutron scattering (SANS), wide-angle X-ray scattering (WAXS) and molecular dynamics simulation (MD). In addition, their adsorption dynamics at the air-water and oil-water interfaces were investigated using ring tensiometry, maximum bubble pressure, spinning drop and dynamic light scattering (DLS). The biosurfactants were found to exhibit a pronounced hydrophilic character, as evidenced by the formation ofWinsor IV microemulsions of rhamnolipid/ethoxylate/n-decane/water systems in the presence of rather hydrophobic ethoxylates. With sophorolipid, Winsor IV microemulsions disappear even on small addition. Furthermore, the catanionic surfactant systems with biosurfactants do not precipitate at equimolar ratios, nor do they form vesicles. The catanionic surfactant systems form micellar structures, whereas equimolar mixtures with rhamnolipid exhibit rod-like structures, capable of incorporating oil. However, evidence suggests that the biosurfactants are not miscible with other surfactants at the nanoscopic scale, presumably due to strong carbohydrate interactions. Consequently, the biosurfactants manifest properties that are both surfactant and lipid-like. In addition, the biosurfactants demonstrate both a typical ionic and nonionic character depending on the measurement technique employed. The structure and efficiency of the microemulsions containing rhamnolipid/ethoxylate/n-decane/water are analogous to those of ethoxylate/ndecane/ water, suggesting minimal influence from rhamnolipid. In contrast, rhamnolipid was found to accelerate the adsorption to interfaces. The research enabled the understanding of the differences between biosurfactants and conventional surfactants, contributing to the development of performing formulations with biosurfactants for applications. | |||||||
| Lizenz: |  Dieses Werk ist lizenziert unter einer Creative Commons Namensnennung 4.0 International Lizenz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Chemie » Physikalische Chemie und Elektrochemie | |||||||
| Dokument erstellt am: | 28.10.2025 | |||||||
| Dateien geändert am: | 28.10.2025 | |||||||
| Promotionsantrag am: | 28.05.2025 | |||||||
| Datum der Promotion: | 23.09.2025 |
