新穎性混成材料及其於光電應用： 高分子/奈米結晶二氧化鈦與高分子/倍半矽氧烷材料

Abstract

由於有機無機混成材料具有調控其彼此之間的特性來製備出各種創新的用途，所以近年來已廣泛地被探討。在混成材料中，二氧化鈦與倍半矽氧烷是兩種重要的奈米結構主體，然而其在光學膜上的應用卻尚未被完全開發與探討清楚，因此本論文的研究目標為設計與合成出新穎的高分子/二氧化鈦或倍半矽氧烷混成材料並探討其在光學膜上的應用，如高折射率薄膜、抗反射膜與光波導元件。 高分子/二氧化鈦混成材料部份，有兩種奈米複合材料被合成與鑑定。在第二章中，將描述有關高折射率聚醯亞胺-奈米晶粒二氧化鈦混成光學材料的合成方法與應用。可溶性、末端帶有酸基的聚醯亞胺將被利用來與四丁基鈦混成製備混成光學材料，此材料二氧化鈦含量可增加至90 wt%並具有1.943的高折射率，而其光學膜也可應用於三層抗反射塗層，在可見光範圍其反射率可小於0.5 %。在第三章中，將描述感光性聚丙烯酸-二氧化鈦混成光學材料的設計與合成。改質過的聚丙烯酸具有一半的壓克力官能基與一半的酸基可被利用來與壓克力官能基化三甲基矽烷修飾過的二氧化鈦前驅物混成製備出感光性光阻，其奈米二氧化鈦晶粒可以水熱法來促進生成且均勻分散於聚丙烯酸高分子中，此光學膜可直接利用黃光顯影製程製備出不同形狀之圖案也具有高折射率性質，因此可應用於抗反射光學膜。 高分子/倍半矽氧烷混成材料部份，有感光性與奈米孔洞混成材料將被合成與鑑定。在第四章中，將闡述以壓克力官能基化的聚氫基倍半矽氧烷與各種壓克力單體製備出感光性光阻，此光阻製備出之光學膜可以黃光顯影製程製作出Y形狀溝道圖案且具有低光傳損失性質，其光學膜也可應用於各種光波導元件上。在第五章中，具有奈米孔洞的聚甲基倍半矽氧烷光學膜可利用二甲基胺官能基化的倍半矽氧烷寡聚物作為孔洞生成劑並以熱燒結方式製備，在此光學膜中其奈米尺寸之孔洞可均勻分布於聚甲基倍半矽氧烷中且具有低介電常數與低折射率性質，在光電元件上可應用於低折射率光學膜與低介電材料。 以上合成出之高分子/二氧化鈦或倍半矽氧烷混成光學材料均具有比原材料更優異的各種光學特性，因此這些混成光學材料可應用於光學與光電元件上，如抗反射膜與光波導。

Organic-inorganic hybrid materials have been extensively studied recently since their molecular tailing properties could produce new functionalities. Titania and silsesquinoxaine represent two important nano-building blocks for hybrid materials. However, hybrid optical films based on these two nano-building blocks have not been fully explored yet. The objectives of this thesis are to synthesize hybrid nanocomposites of polymer/titania or silsesquioxane and explore their optical applications, including high refractive index films, antireflective films, and optical waveguides. Two classes of polymer/nanocrystalline titania hybrids are synthesized and characterized. The methodology and procedures for high refractive index polyimide nanocrystalline-titania (PI-TiO2) hybrid optical materials are described in Chapter 2. A soluble polyimide with carboxylic acid end groups is formulated with titanium n-butoxide to yield the hybrid materials. The titania content could be as high as 90 wt% and thus a relative high refractive index of 1.943 could be obtained. It also demonstrates the application in three-layer anti-reflective coating and the reflectance is less than 0.5 % in the visible range. Besides, photosensitive poly(acrylic acid) – titania (PAA-TiO2) hybrid optical materials are synthesized and described in Chapter 3. Poly(acrylic acid) grafted with half degree of poly(ethylene glycol methacrylate) are formulated with titania modified with 3-methacryloxypropyl trimethoxysilane to yield the resist. Nanocrystalline titania could be generated by further hydrothermal treatment and well dispersed in the polymeric matrices. The hybrid films could be also patterned by a direct lithographic process and have high refractive index. These materials might have the potential applications in antireflection coating devices. For silsesquioxane-based nanocomposites, photosensitive or porous hybrid materials are synthesized and characterized. In Chapter 4, Propargyl methacrylate - functionalized poly(hydrogen silsesquioxanes) (PHSSQ-PMA) is synthesized by hydrosilylation and then formulated with acrylic monomer mixtures to yield the photosensitive optical hybrid materials. The hybrid materials could be developed to Y-shape channel patterns and have the applications in different optical waveguides. An example of nanoporous poly(methyl silsesquioxane) (Nanoporous PMSSQ) thin films fabricated through thermally sacrificing a new porogen, dimethylamino-functionalized polyhedral oligomeric silsesquioxane is presented in Chapter 5. Nano-size pores are homogeneously dispersed in PMSSQ matrices. Meanwhile, the low refractive index and the low dielectric constant could be obtained. The nanoporous thin films suggest the potential applications in low refractive index films and low-k dielectrics. The above titania or silsesquioxane based hybrid materials exhibit superior optical characteristics than their parent polymers. Such materials would be of interest in various optical and optoelectronic devices, such as antireflective films and optical waveguides… etc.