新型含硫之聚醯亞胺-二氧化鈦混成奈米複合光學材料之設計、合成與其性質研究

Abstract

芳香族聚醯亞胺在光學元件上的應用非常有潛力，但是其應用性受限於低溶解度及難熔性。導入羥基於聚醯亞胺結構中是一個重要的方法，不僅可以有效地提升溶解度，並且提供了有機及無機材料鍵結的反應位置。由於有機/無機混成材料較其單一材料具有機械性質、熱性質、及光學性質上的提昇效果，因此近年來已逐漸受到重視及研究。本研究致力於設計與合成出新穎的高分子/二氧化鈦混成材料並探討其在光學膜上的應用，進而製作出具透明性且高折射率光學膜。 分子設計除了導入羥基，為了達到高折射率及穿透度的目標，還做了其他的元素導入。可增加分子極化率的元素，如硫及氧的元素可增加高分子材料的折射率，而具拉電子的官能基或者酯環化合物則可增加高分子材料的穿透度。 在第二章中，以兩個二胺單體分別含有羥基及六氟官能基與二酸酐(ODPA)製備新穎的可溶性共聚醯亞胺。具有羥基的共聚醯亞胺與四丁基鈦可進一步藉由控制有機/無機莫耳比例成功地製備有機/無機混成光學材料。此光學薄膜(100-500 nm)的折射率可由二氧化鈦含量自由地調控(1.66-1.87)。甚至我們也成功合成出二氧化鈦含量達50 %的光學厚膜(20-30 μm)，其光學厚膜同時具有高撓曲性、高機械強度、出色的熱性質、低熱膨脹係數、高折射率，及可見光區的高穿透度。 在第三章中，合成兩個具羥基，且分別含有硫以及芴的新型二胺，與二酸酐(ODPA和6FDA)合成出兩系列新穎的聚醯亞胺，其中一系列具醚鏈結構，另一系列則全是硫的連結，已達使材料有高折射率極高穿透度的目的。具有羥基的聚醯亞胺與四丁基鈦可進一步藉由控制有機/無機莫耳比例成功地製備有機/無機混成光學材料。此光學薄膜(100-500 nm)的折射率可由二氧化鈦含量自由地調控(1.64-1.87)。我們成功的合成出二氧化鈦含量達50 %的光學厚膜(10-15 μm)。此系統的光學厚膜亦具有高撓曲性、高機械強度、出色的熱性質、低熱膨脹係數、高折射率，及可見光區的高穿透度。

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.