Design, Synthesis, and Characterizations of Novel Sulfur-containing Aromatic Polyimide-Nanocrystalline-Titania Hybrid Optical Materials
| Autor: | Pei-Hsuang Wang, 王珮璇 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 Aromatic polyimides with high refractive index could be potentially useful for optoelectronic devices. However, their applicability has usually been limited because of the normally insolubility and infusibility in the fully imidized form. The incorporation of hydroxyl groups on the backbones of the polyimides was an important strategy to ensure the solubility and provided the reactive sites for organic-inorganic bonding. Composites that consist of polymer–inorganic hybrid materials have recently attracted considerable interests due to their enhanced mechanical, thermal, optical properties compared to the corresponding individual inorganic or polymer component. The goal of this study is to develop novel polymer/titania hybrid materials and investigated their applications in optical films. Furthermore, high optical transparency, and high refractive index optical films could also be prepared. Besides the hydroxyl group, the molecular design approach is applied to reach the high refractive index and transparency goal. The introduction of high polarizability moieties, such as sulfur and oxygen element could make the higher refractive index, and the electron-withdrawing group, such as hexafluorosiopropylidene (6F) group result the high transparency. Chapter 2 prepared the novel soluble co-polyimide with hydroxy- and –CF3-substituted diamine, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, and the sulfur-containing diamine, bis(4-aminophenyl) sulfide, with commercial tetracarboxylic dianhydride ODPA. High refractive index co-polyimide–titania hybrid optical films were successfully prepared from the soluble hydroxy-substituted co-polyimide and titanium butoxide by controlling the organic/inorganic molar ratio. The tunable refractive index (1.66-1.87) of hybrid thin films (100-500 nm) could be obtained by controlling titania content. Moreover, the thick titania hybrid films could also be achieved even with the relatively high titania content as high as 50 wt%. All these obtained hybrid thick films (20-30 µm in thickness) revealed excellent thermal properties with low CTE, good mechanical properties and flexibility, high refractive index, and good optical transparency in the visible region. Chapter 3 included two series of novel soluble polyimides, one is ether type, the other is sulfur-linkage, with hydroxy-substituted which were synthesized from the new diamines, 9,9-bis(4-(4-amino-3-hydroxyphenoxy)phenyl)fluorene and 4,4’-bis(4-amino-3-hydroxyphenylthio)diphenylsulfide, with two commercial tetracarboxylic dianhydride, ODPA and 6FDA, respectively. High refractive index polyimide–titania hybrid optical films were successfully prepared from the soluble hydroxy-substituted polyimides and titanium butoxide by controlling the organic/inorganic molar ratio. The tunable refractive index (1.64-1.87) of hybrid thin films (100-500 nm) could be obtained by controlling titania content. Moreover, the thick titania hybrid films could also be achieved even with the relatively high titania content as high as 50 wt%. All these obtained hybrid thick films (10-15 µm in thickness) revealed excellent thermal properties with low CTE, good mechanical properties and flexibility, high refractive index, and good optical transparency in the visible region. |
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