Dokument: Multifunctional PNIPAM-based Copolymer Microgels: From Structural Inhomogeneities to Nanoreactors for Hybrid Microgels
| Titel: | Multifunctional PNIPAM-based Copolymer Microgels: From Structural Inhomogeneities to Nanoreactors for Hybrid Microgels | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=64318 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20231218-090658-2 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Otten, Marius [Autor] | |||||||
| Dateien: |
| |||||||
| Beitragende: | Prof. Dr. Karg, Matthias [Gutachter] Prof. Dr. Hellweg, Thomas [Gutachter] | |||||||
| Stichwörter: | PNIPAM Microgels, Volume Phase Transition, Thermoresponsive Polymers, Nanoparticles, Light Scattering, Ultraviolet–visible Spectroscopy, Transmission Electron Microscopy | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 540 Chemie | |||||||
| Beschreibung: | Chemical and/or physical crosslinking of polymer chains can lead to the formation of micro- or nanometer sized gel-like networks that are known as micro- and nanogels. These soft, deformable objects can react to external stimuli like pH or temperature, which enable microgels to either take up, hold or release solvent resulting in a change of the effective size. These “smart” characteristics make microgels interesting for various applications such as drug delivery or as responsive coatings. The combination of soft microgels with inorganic nanoparticles can further extend the properties of such systems which therefore gain increased interest in research fields like sensing or catalysis. Furthermore, the incorporation of multiple different monomers into microgel networks can result in systems with a more complex architecture and enhanced properties. This increased complexity can be interesting for applications as well as fundamental research. For certain applications, the introduction of functional groups that can bind enzymes or complex ions can be useful while fundamental research is interested in the potential to mimic more complex (bio)molecules using soft particles with specific structures and properties. The characterization of those systems with scattering and microscopic techniques plays an important role to understand the morphology of those systems. Resolving the inner structure of microgel is challenging due to the complex architecture. Results from small-angle neutron scattering revealed a fuzzy sphere model for microgels where the core of the network is rather densely crosslinked and the outer periphery consists of loosely crosslinked polymer chains.
In this thesis, complex copolymer microgels were synthesized as nanoreactors for the in situ formation of gold nanoparticles. In the past, only few studies revolved around the controlled in situ synthesis of nanoparticles within microgels, as seeded precipitation polymerization is typically a reliable strategy to introduce single nanoparticles into microgel networks. In this work, the influence of comonomers on the in situ synthesis has been systematically studied to open a new synthesis route for hybrid microgels. A successful formation of a single gold nanoparticle in each individual microgel could be achieved by incorporation of two functional comonomers. The characterization of the complex microgels via scattering techniques, including dynamic light scattering and small-angle X-ray scattering but also imaging via transmission electron microscopy indicated a domain like structure of the networks that favors the localized accumulation of gold ions and thereby allows for the controlled in situ synthesis. Typically, X-ray and neutron scattering experiments are used to address the structure on a local scale but come with the disadvantage of being complex and costly. In this thesis, the correlation of data from dynamic light scattering and absorbance spectroscopy was evaluated as an alternative approach that can provide insights into structural inhomogeneities and deviation from the established fuzzy sphere morphology. Therefore, a systematic study of three different types of microgels was carried out to prove the significance of this analytical methodology. The comparison of “classical” PNIPAM microgels, copolymer microgels and core-shell microgels revealed a dependency between the swelling behavior and the inner structure. As a consequence, the combination of temperature-dependent dynamic light scattering and temperature dependent ultraviolet-visible absorbance spectroscopy was identified as promising towards an accessible and fast characterization of microgels that can potentially be automatized to study and categorize larger numbers of systems. | |||||||
| 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: | 18.12.2023 | |||||||
| Dateien geändert am: | 18.12.2023 | |||||||
| Promotionsantrag am: | 29.08.2023 | |||||||
| Datum der Promotion: | 30.11.2023 |
