Dokument: Hard Core-Soft Shell Microgels at Interfaces
| Titel: | Hard Core-Soft Shell Microgels at Interfaces | |||||||
| Weiterer Titel: | Hartkern-Weichschalen-Mikrogele an Grenzflächen | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=64844 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20240209-140304-8 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Kuk, Keumkyung [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Karg, Matthias [Gutachter] Jun-Prof. Dr. Buttinoni, Ivo [Gutachter] | |||||||
| Stichwörter: | Colloidal monolayers, Microgels, Small-angle light scattering, Thin film interference, Drying dynamics | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 540 Chemie | |||||||
| Beschreibung: | Poly(N-isopropylacrylamide) or PNIPAM microgels, are now well-known due to their stimuli-responsive nature, which has offered exciting opportunities to tune interactions, packing fractions, and drug release on demand. Such microgels—soft and deformable crosslinked polymer networks—have demonstrated their suitability as a model system, a highly tailorable soft counterpart of the already established hard sphere model systems. They are also readily adsorbed at fluid/liquid interfaces and have been shown to effectively stabilise emulsions and foams. Unlike hard spheres or similar systems, however, microgels exhibit elastic deformation at the interface in response to interfacial tension, resulting in complex morphologies with combined properties of the polymer, colloid, and solvent. This thesis focuses on interactions among such microgels at fluid/liquid interfaces. It encompasses the synthesis and fluid interface-assisted assembly of these microgels, as well as their interaction with various solid surfaces during the deposition onto substrates.
Micron-sized silica-PNIPAM core-shell (CS) microgels were synthesised as model systems using seeded precipitation polymerisation. The proposed batch synthesis protocol allows control over the shell-to-core size ratio in a wide range of dimensions. These core-shell microgels are specifically designed to have high optical contrast as well as a suitable interparticle distance for small-angle light scattering and various microscopic techniques, enabling in situ monitoring of the interfacial behaviour of such microgels in both reciprocal and real spaces. Through our model systems, we aim to bridge the research gap stemming from the difficulty of visualising at the individual microgel level. The synthesised CS microgels with various dimensions were assembled at the air/water interface using the Langmuir trough combined with the small-angle light scattering setup (LT-SALS). The assembly behaviour of the microgels was also investigated by means of microscopy. The in situ measurement results from the reciprocal and real spaces were compared. The comparison between these two complementary methods showed a strong agreement. However, when compared with ex situ results—after the deposition onto a solid substrate—we found significant differences in the microstructure of the microgels. Video microscopy of drying microgel films (soft colloidal monolayer) on different substrates unveiled a complex drying scenario influenced by the wettability of the substrate, the elasticity of individual microgels, and the surface pressure of the microgel-laden interface. By considering CS microgels with three different crosslinker densities, we identified two key elements, which govern the drying process of such microgel films on a substrate: the microgel-to-substrate adhesion and the immersion capillary force. Our argument finds support in various complementary measurements, including thin film pressure balance, film thickness analysis coupled with particle tracking, as well as molecular dynamics simulations. In future work, we hope that our results can facilitate the development of a more comprehensive theoretical framework for elucidating the interfacial behaviour of soft matter. | |||||||
| 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: | 09.02.2024 | |||||||
| Dateien geändert am: | 09.02.2024 | |||||||
| Promotionsantrag am: | 02.01.2024 | |||||||
| Datum der Promotion: | 31.01.2024 |
