Boyaciyan, Dikran (2019)
Functional coatings with colorimetric properties: the influence of electrostatic interaction and hydrogen bonding on the assembly of gold nanoparticles in polymer brushes.
Technische Universität Darmstadt
Dissertation, Erstveröffentlichung
Kurzbeschreibung (Abstract)
The modification of surfaces with thin films is widely used to tailor physical and chemical properties of surfaces. This approach can provide "smart" surfaces with desired tunable properties. Polymer brushes represent a class of thin films, where the polymer chains are chemically end-grafted to the substrate. The chain functionality can be tailored by chemical composition, which allows the brushes to respond to external stimuli. In addition, polymer brushes may sterically stabilize colloids. Thus, polymer brushes are suitable candidates as a matrix for the incorporation of inorganic nanoparticles, like gold nanoparticles (AuNPs). AuNPs induce optical properties due to their surface plasmon resonance (SPR), which results in smart nanocomposite materials with tunable optical properties for the application as colorimetric sensors. The ability to control the particle amount and distribution within a brush matrix has a strong impact on fabrication of colorimetric sensors with optical properties on demand.
In order to achieve brush/AuNP composites with desired properties, the thesis focuses on the impact of electrostatic interaction and hydrogen bonding on the formation of brush/AuNP composite materials. Here, pH-sensitive AuNPs are embedded into strong cationic and non-ionic polymer brushes. The electrostatic interactions and hydrogen bondings are tuned by changing the surface charge of the AuNPs through variations of pH value, while the charges of the brushes are not affected.
The first part of the present thesis presents the assembly of pH-sensitive AuNPs into cationic polyelectrolyte brushes. In particular, the synergistic use of different characterization techniques clarify directly and indirectly effects of the electrostatic interaction on the structure, morphology and sensitivity of cationic brush/AuNP composites.
The second part discusses the influence of using a non-ionic polymer brush on the assembly of pH-sensitive AuNPs. It is shown, that the nature of polymer brush has a crucial impact on the stabilization of incorporated AuNPs. This work demonstrates a novel approach to incorporate negatively charged AuNPs into non-ionic polymer brushes by using an electric field. Finally, the quality of brush/AuNP composites was experimental evaluated in terms of the long-term stability for the future prospect as colorimetric sensors.
The thesis presents a fundamental understanding of smart coatings, where the particle-particle interaction as well as particle-brush interaction can be simply controlled by variation in pH value and governs their structure and responsive behavior.
Typ des Eintrags: | Dissertation | ||||
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Erschienen: | 2019 | ||||
Autor(en): | Boyaciyan, Dikran | ||||
Art des Eintrags: | Erstveröffentlichung | ||||
Titel: | Functional coatings with colorimetric properties: the influence of electrostatic interaction and hydrogen bonding on the assembly of gold nanoparticles in polymer brushes | ||||
Sprache: | Englisch | ||||
Referenten: | von Klitzing, Prof. Dr. Regine ; Biesalski, Prof. Dr. Markus | ||||
Publikationsjahr: | 2019 | ||||
Ort: | Darmstadt | ||||
Datum der mündlichen Prüfung: | 17 Dezember 2018 | ||||
URL / URN: | https://tuprints.ulb.tu-darmstadt.de/8359 | ||||
Kurzbeschreibung (Abstract): | The modification of surfaces with thin films is widely used to tailor physical and chemical properties of surfaces. This approach can provide "smart" surfaces with desired tunable properties. Polymer brushes represent a class of thin films, where the polymer chains are chemically end-grafted to the substrate. The chain functionality can be tailored by chemical composition, which allows the brushes to respond to external stimuli. In addition, polymer brushes may sterically stabilize colloids. Thus, polymer brushes are suitable candidates as a matrix for the incorporation of inorganic nanoparticles, like gold nanoparticles (AuNPs). AuNPs induce optical properties due to their surface plasmon resonance (SPR), which results in smart nanocomposite materials with tunable optical properties for the application as colorimetric sensors. The ability to control the particle amount and distribution within a brush matrix has a strong impact on fabrication of colorimetric sensors with optical properties on demand. In order to achieve brush/AuNP composites with desired properties, the thesis focuses on the impact of electrostatic interaction and hydrogen bonding on the formation of brush/AuNP composite materials. Here, pH-sensitive AuNPs are embedded into strong cationic and non-ionic polymer brushes. The electrostatic interactions and hydrogen bondings are tuned by changing the surface charge of the AuNPs through variations of pH value, while the charges of the brushes are not affected. The first part of the present thesis presents the assembly of pH-sensitive AuNPs into cationic polyelectrolyte brushes. In particular, the synergistic use of different characterization techniques clarify directly and indirectly effects of the electrostatic interaction on the structure, morphology and sensitivity of cationic brush/AuNP composites. The second part discusses the influence of using a non-ionic polymer brush on the assembly of pH-sensitive AuNPs. It is shown, that the nature of polymer brush has a crucial impact on the stabilization of incorporated AuNPs. This work demonstrates a novel approach to incorporate negatively charged AuNPs into non-ionic polymer brushes by using an electric field. Finally, the quality of brush/AuNP composites was experimental evaluated in terms of the long-term stability for the future prospect as colorimetric sensors. The thesis presents a fundamental understanding of smart coatings, where the particle-particle interaction as well as particle-brush interaction can be simply controlled by variation in pH value and governs their structure and responsive behavior. |
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Alternatives oder übersetztes Abstract: |
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URN: | urn:nbn:de:tuda-tuprints-83595 | ||||
Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 500 Naturwissenschaften und Mathematik > 530 Physik 500 Naturwissenschaften und Mathematik > 540 Chemie |
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Fachbereich(e)/-gebiet(e): | 05 Fachbereich Physik 05 Fachbereich Physik > Institut für Festkörperphysik (2021 umbenannt in Institut für Physik Kondensierter Materie (IPKM)) |
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Hinterlegungsdatum: | 27 Jan 2019 20:55 | ||||
Letzte Änderung: | 27 Jan 2019 20:55 | ||||
PPN: | |||||
Referenten: | von Klitzing, Prof. Dr. Regine ; Biesalski, Prof. Dr. Markus | ||||
Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | 17 Dezember 2018 | ||||
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