Design, Synthesis, and Properties of Polyimides and Their Hybrid Materials for Optical Device Applications

本文藉由理論與實驗探討聚醯亞胺之分子結構與其近紅外光區光學性質之關係。並合成相容性更佳之新型聚醯亞胺/氧化矽混成材料。最後製備可進行直接微影程序之感光性聚醯亞胺/氧化矽混成材料以製作通道性光波導。 本文的第一部份由量子化學的角度探討分子結構對分子於近紅外光的振動吸收之影響。由實驗與量子化學計算的結果顯示，當聚醯亞胺之雙胺部份的橋接官能基之拉電子能力不同時，會造成苯環上碳氫鍵長之變化，而使得碳氫鍵之振動頻率（包含基頻及倍頻）產生偏移。當橋接官能基的拉電子能力越強時，會使得碳氫鍵縮短而提高振動頻率。僅藉由改變橋基官能基由-CH2-至-SO2-即可使碳氫鍵於近紅外光區的第一倍頻吸收位置偏移約20nm，第二倍頻吸收位置偏移約10 nm。且由於分子結構使倍頻吸收位置產生偏移，會影響到聚醯亞胺所製備平面光波導之光傳損失。以PMDA/DPM與PMDA/ODA為例，雖然PMDA/DPM具有較高的C-H鍵密度，但由於其C-H鍵較長使得其振動吸收位置往長波長處偏移，造成以PMDA/DPM所製備的光波導在波長1310nm處的光傳損失反而比PMDA/ODA來得低。 本文第二部份探討聚醯亞胺/氧化矽混成材料的合成與性質。聚醯亞胺為傳統之高性能高分子，被廣泛地使用在微電子等產業中，聚醯亞胺/氧化矽混成材料可進一步提高其熱性質與機械性質而獲得廣泛地研究。本研究利用GOTMS作為分子間作用力（氫鍵）之耦合基與APrTMS作為分子內耦合基（共價鍵），可以同時保留聚醯亞胺的優秀熱穩定性同時使混成的氧化矽顆粒均勻的分散其內。藉由TEM照片可知本研究逤製備之混成材料，其氧化矽顆粒大小僅有5nm，可將非必要之光散射損失降至最低。此外聚醯亞胺的熱穩定性亦可藉由加入氧化矽而提高。由於奈米等級分散的氧化矽顆粒與聚醯亞胺藉由分子內與分子間耦合基形成類似交聯構造，使得聚醯亞胺的熱膨脹係數在加入氧化矽後從原本的123.4-726.9 ppm/℃ 大幅降低為16.6-44 pm/℃。所合成的聚醯亞胺/氧化矽混成材料之介電常數為2.85-3.73，波長1310nm處的光傳損失為0.5-1.9 dB/cm，具有應用在低介電常數材料或光波導材料上之潛力。 本文第三部份探討感光性聚醯亞胺/氧化矽混成材料的合成與性質。聚醯亞胺/氧化矽混成材料雖已受到廣泛的研究，但傳統的微影製程需要較多的製程步驟與較長的製程時間。本文在聚醯亞胺鏈段上導入離子型之未飽和基團MDAE，在氧化矽部份則導入未飽和基團MPTMS，加入光起始劑反應後可使其為負型之感光性材料，以直接進行曝光顯影與圖型轉移之步驟。感光性聚醯亞胺/氧化矽混成材料具有較原本之聚醯亞胺更為優秀之耐熱性質，同時在其熱固化的過程中，體積的收縮極小，可避免固化後圖型產生變型進而提高材料的微影解析度。以感光性聚醯亞胺/氧化矽混成材料製作通道型光學波導具有折射率易調控，熱穩定性佳，熱膨脹係數較低，與低光傳損失等優點。且此一方法可直接應用於目前大部份之聚醯亞胺/金屬氧化物混成材料中，使其能夠直接進行光學微影圖型化以節省製程所需之時間。且由於此感光性聚醯亞胺/氧化矽混成材料對有機與無機材料之相容性俱佳，可以之掺雜有機發光基團（dye），稀土元素（Lanthanide），或是半導體奈米晶體等（e.g. CdS），使其成為可直接進行光學微影之主動性材料以應用於非線性光學（NLO-EO）、EL、PL、Amplifier等領域上。In this dissertation, both theoretical and experimental studies were used to correlate the near-infrared optical properties with the molecular structures of polyimides. Besides, new polyimide/silica hybrid materials were developed to improve the physical properties of their parent polyimides. Low loss, low volume shrinkage photosensitive polyimide/silica hybrid materials were also synthesized for fabricating channel optical waveguides. In the first part of this dissertation, “the chemical structure-near infrared optical property” relationship was investigated by both ab initio calculations and experiments. In Chapter 2, the substituents effects of several benzene derivatives on their C-H vibrational frequencies including fundamentals and overtones were investigated. It was found that the electron-withdrawing ability of substituents would influence the bond lengths of other C-H bonds on the aromatic ring: the stronger the electron-withdrawing ability, the shorter the adjacent C-H bond length; and the shorter C-H bonds will vibrate at higher frequencies. This characteristic can be utilized to tune the absorption position of C-H vibrational overtones in the near-infrared region. The maximum shifting of absorption positions was 30nm for the first overtones, and 15nm for the second overtones. In Chapter 3, the similar concept was extended to the polyimides. Polyimides stand for a potential candidate of materials for high performance and low cost optical waveguides. For polymers, their C-H absorption loss in the near-infrared region is critical for optical waveguide applications. In this chapter, several diamines bearing different bridge groups with different electron-withdrawing ability were used to investigate the effects of these bridge groups on the near-infrared optical properties of diamines and polyimides (synthesized with the dianhydride PMDA). It was found that the electron-withdrawing ability also could influence the C-H vibrational overtone absorption positions in the near-infrared region. Their absorption positions can be shifted up to 20nm for the first overtone, and 10nm for the second overtone. The planar waveguides of these polyimides were fabricated to investigate if the shifting of absorption band would influence their apparent optical loss. And it was found that PMDA/DPM stands for a lower optical loss at the wavelength of 1310nm than PMDA/ODA though its higher C-H number density than PMDA/ODA. In the second part of this dissertation (Chapter 4), a new method to produce nano-sized silica particles in polyimide/silica hybrid materials was proposed. By using both inter- and intra-molecular interactions between polyimide and silica can improve their compatibility most. APrTEOS was used as the intermolecular coupling agents by covalently bonded to the ends of polyimides, and GOTMS was used as intramolecular coupling agents by the formation of hydrogen bonds between the end diols of GOTMS and carbonyl groups of polyimides. By this method, it was found that the size of silica particles can be reduced to 5nm. And their coefficients of thermal expansion can be reduced to about 2 orders in comparison with their parent polyimides. In the third part of this dissertation (Chapter 5), a new synthesis scheme was proposed to produce photo-patternable polyimide/silica hybrid materials. By introducing the photosensitive compound of MDAE via the formation of acid/base ionic salts between tertiary amines of MDAE and carboxylic acid of poly(amic acid), the polyimide/silica hybrid materials can be patterned by direct photo-lithography acting as a negative tone photoresist. Besides MDAE, a trifunctional silane bearing a unsaturated methacrylate substituents, MPTMS, was incorporated to the silica moieties of polyimide/silica hybrid materials. In conventional ionic salt photosensitive polyimide, the volume shrinkage is considerable because all MDAE will be removed from films after the complete imidization (no more ionic salts). The incorporation of MPTMS can reduce the volume shrinkage of polyimide/silica hybrid materials to low during the curing processes, because part of MDAE was photo-crosslinked with MPTMS after the exposure step. The volume shrinkage was reduced to <10% for Polyimide/SiO2/MPTMS in comparison with >20% of that for polyimide. The prepared low shrinkage Polyimide/SiO2/MPTMS hybrid materials exhibit good lithographic resolution, excellent thermal stability, and tunable refractive indices.中文摘要.p1 Abstract.p3 Contents.p6 Table Captions.p10 Figure Captions.p12 Chapter 1 Design, Synthesis, and Properties of Polymers and Their Hybrids for Optical Waveguide Applications.p1 Chapter 2 Model Compound Studies: Effect of Molecular Structures on the C-H Overtone Spectra and Bond Lengths of Benzene Derivatives.p103 Chapter 3 Monomer and Polymer Studies: Effects of Molecular Structures on the Near-Infrared Optical Properties of Polyimides and Their Corresponding Optical Planar Waveguides.p137 Chapter 4 Synthesis and Characterization of Polyimide/Silica Hybrid Materials: An Approach through Both Interchain and Intrachain Interactions toward Monodispersed Nanosize Silica Particles. p160 Chapter 5 Low Volume Shrinkage Photo-patternable Polyimide/Silica Hybrid Materials for Low-loss Optical Waveguides.p184 Chapter 6 Conclusions and Future Works.p211 Autobiography and publication list.p21