Dokument: Soft core-shell particles at fluid interfaces: theory and experiment
| Titel: | Soft core-shell particles at fluid interfaces: theory and experiment | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=60763 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20221107-101044-9 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Kolker, Jannis Hendrik [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Löwen, Hartmut [Gutachter] Janssen, Liesbeth M. C. [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 530 Physik | |||||||
| Beschreibung: | In the research field of condensed matter, soft core-shell systems represent a wide range of complex systems with fundamental and applied relevance. Whether in general or in the case of specifically polymeric structured systems, such as microgels or polymer-grafted cores (hairy particles), core-shell systems offer a wide range of phenomena and effects at all levels of coarseness. In combination with the effects of an acting fluid interface on the core-shell system, static and dynamic phenomena such as forming effects of coronae at the interface and hysteresis can occur.
Therefore, this thesis is divided into two parts, on the one hand core-shell systems in contact with a fluid interface are investigated for their elastic properties in general and on the other hand more structured systems, such as microgels or polymer grafted cores (hairy particles), are investigated for their special (bulk) properties at the interface. This investigation ranges from the (static) interaction at the interface of coronae to (dynamic) hysteresis effects when the solvent conditions change. The general investigation of a coarse-grained core-shell system with a coupled architecture at an (equatorially acting) interface provides a complete analysis of the linear response to such an interfacial loading and includes the investigation of the deformation behaviour for different stiffnesses as well as different size ratios for the core and the shell. Different Poisson ratios including different degrees of auxeticity are also analysed, giving insight into the deformation behaviour of such a material/systems. In addition, the stress field is investigated, revealing inhomogeneous stress behaviour within the deformed core-shell system. However, the study of polymeric structured systems, such as microgels or polymer-grafted cores (hairy particles), and their properties provides insight into how their (static) bulk phenomena are affected by the presence of an fluid interface. While both systems form a corona at the interface in a (more) diluted situation (single-body system), microgels show core-hysteresis for their widely studied bulk volume phase transition. Furthermore, they (microgels, as a many-body system) induce different types of interactions between interfaces for different solvent conditions. In this thesis, the core-hysteresis is quantified by the lateral expansion and the surface pressure at the interface, while the induced interaction between two interfaces packed with microgels is verified by the effective osmotic pressure between the two interfaces. The (single-body) core-hysteresis is further investigated as a function of the crosslinker density, revealing that a lower crosslinker density causes a larger amount of hysteresis. No hysteresis is found in the comparative situation in the bulk. Therefore, the adsorbed initial state is considered as a particular kinetically trapped state. However, the interaction between the interfaces is studied in more detail as a function of the density of the microgel itself (in the many-body system and the solvent conditions), for which different osmotic pressures occur. In particular, when the microgel packing is (more) diluted and solvent conditions are poor, a negative osmotic pressure is found, while in all other situations (dense microgel packing and/or good solvent conditions) a positive osmotic pressure occurs. For the polymer grafted cores (hairy particles), the effective interaction between the core and the interface is explicitly investigated under good solvent conditions, resulting in an equilibrium distance of the core to the interface. In addition, the effective pair interaction between the two cores induced by the corona formed at the interface is analysed and found to be repulsive. A similar set-up in the bulk also reveals a repulsive effective pair interaction. Established effective pair interactions such as the Jagla or star polymer interaction are fitted to the data and provide information on effective (intrinsic) parameters such as the effective corona and core size or the effective softness of the Jagla potential. | |||||||
| Lizenz: |  Dieses Werk ist lizenziert unter einer Creative Commons Namensnennung 4.0 International Lizenz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Physik » Physik der kondensierten Materie | |||||||
| Dokument erstellt am: | 07.11.2022 | |||||||
| Dateien geändert am: | 07.11.2022 | |||||||
| Promotionsantrag am: | 15.06.2022 | |||||||
| Datum der Promotion: | 20.09.2022 |
