Braun, Tom (2018)
Synthesis and Characterization of Functional Thin Ultra-Low Density Coatings Inside Hollow Spheres.
Technische Universität Darmstadt
Dissertation, Erstveröffentlichung
Kurzbeschreibung (Abstract)
Uniform coatings on the inner surface of hollow spheres have applications in optical devices, time- or site-controlled drug release, and heat storage devices. Spherical shells that contain a thin layer of ultra-low density polymer foam have also attracted attention in the inertial confinement fusion community where they can be used to bring dopants for diagnostics and nuclear physics experiments in direct contact with the deuterium-tritium (DT) fuel or to study new ignition regimes by enabling the formation of uniform liquid DT fuel layers. The uniformity of these coatings is often critical for the application performance and, therefore, requires precise understanding and control over the coating process and its parameters.
Rather than trying to fabricate free-standing foam shells, as it was reproducibly done in the fusion community, a new approach can be explored: using prefabricated hollow spherical shells as molds to cast concentric, thin-walled, low-density foam layers using sol-gel chemistry. For this purpose, a molecular precursor solution is inserted into the shell through a tiny hole using a pressure gradient filling process, where it transforms into a high-viscosity polymer fluid and ultimately gels during rotation, creating a uniform gel layer. The remaining solvent is then removed from the shell via supercritical drying, leaving a uniform, ultra-low density aerogel layer in the sphere.
This thesis presents a detailed step by step study on the synthesis and characterization of functional, ultra-low density coatings inside hollow spheres using this novel approach. It will describe how polymer-based sol–gel chemistry can be utilized to achieve ultra-low density coatings and report on in situ real-time radiography experiments that provide critical spatiotemporal information about the distribution of fluids inside hollow spheres during uniaxial rotation. An approach to remove the solvent from the gel in the shell without damaging the coated layer is presented and lastly a methodology on casting doped polymer films on the inside of spherical capsules is developed.
| Typ des Eintrags: | Dissertation | ||||
|---|---|---|---|---|---|
| Erschienen: | 2018 | ||||
| Autor(en): | Braun, Tom | ||||
| Art des Eintrags: | Erstveröffentlichung | ||||
| Titel: | Synthesis and Characterization of Functional Thin Ultra-Low Density Coatings Inside Hollow Spheres | ||||
| Sprache: | Englisch | ||||
| Referenten: | Hahn, Prof. Horst ; Donner, Prof. Wolfgang | ||||
| Publikationsjahr: | 2018 | ||||
| Ort: | Darmstadt | ||||
| Datum der mündlichen Prüfung: | 13 Juli 2018 | ||||
| URL / URN: | https://tuprints.ulb.tu-darmstadt.de/7768 | ||||
| Kurzbeschreibung (Abstract): | Uniform coatings on the inner surface of hollow spheres have applications in optical devices, time- or site-controlled drug release, and heat storage devices. Spherical shells that contain a thin layer of ultra-low density polymer foam have also attracted attention in the inertial confinement fusion community where they can be used to bring dopants for diagnostics and nuclear physics experiments in direct contact with the deuterium-tritium (DT) fuel or to study new ignition regimes by enabling the formation of uniform liquid DT fuel layers. The uniformity of these coatings is often critical for the application performance and, therefore, requires precise understanding and control over the coating process and its parameters. Rather than trying to fabricate free-standing foam shells, as it was reproducibly done in the fusion community, a new approach can be explored: using prefabricated hollow spherical shells as molds to cast concentric, thin-walled, low-density foam layers using sol-gel chemistry. For this purpose, a molecular precursor solution is inserted into the shell through a tiny hole using a pressure gradient filling process, where it transforms into a high-viscosity polymer fluid and ultimately gels during rotation, creating a uniform gel layer. The remaining solvent is then removed from the shell via supercritical drying, leaving a uniform, ultra-low density aerogel layer in the sphere. This thesis presents a detailed step by step study on the synthesis and characterization of functional, ultra-low density coatings inside hollow spheres using this novel approach. It will describe how polymer-based sol–gel chemistry can be utilized to achieve ultra-low density coatings and report on in situ real-time radiography experiments that provide critical spatiotemporal information about the distribution of fluids inside hollow spheres during uniaxial rotation. An approach to remove the solvent from the gel in the shell without damaging the coated layer is presented and lastly a methodology on casting doped polymer films on the inside of spherical capsules is developed. |
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| URN: | urn:nbn:de:tuda-tuprints-77687 | ||||
| Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 500 Naturwissenschaften und Mathematik > 500 Naturwissenschaften 500 Naturwissenschaften und Mathematik > 530 Physik 500 Naturwissenschaften und Mathematik > 540 Chemie 600 Technik, Medizin, angewandte Wissenschaften > 600 Technik 600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften und Maschinenbau |
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| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft |
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| Hinterlegungsdatum: | 14 Okt 2018 19:55 | ||||
| Letzte Änderung: | 14 Okt 2018 19:55 | ||||
| PPN: | |||||
| Referenten: | Hahn, Prof. Horst ; Donner, Prof. Wolfgang | ||||
| Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | 13 Juli 2018 | ||||
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| Suche nach Titel in: | TUfind oder in Google | ||||
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