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標題: Preparation and Characterization of Organoclays Based on Dendrons, and Their Self-Assembly Behavior for Electro-Optics
作者: 吳天豪
Wu, Tain-Hao
關鍵字: Nonlinear optical;二次非線性光學;Dendrons;Montmorillonite;Polyimide;Self-assembly;樹枝狀分子;蒙脫土;聚亞醯胺;自組裝排列
出版社: 化學工程學系所
In this study, a bifunctional building block compound,IPDA was used as a building block to synthesize a series of novel polyurethane/malonamide dendrons with azobenzene dyes (disperse red 1, DR1) in the exterior via a convergent route. All of the dendrons (G1, Mw = 1192 ; G2, Mw = 2948 ; G3, Mw = 6459) exhibited structural characteristics with secondary amines located on one end. With this feature, the amine salt was easily formed by the addition of hydrochloric acid. Subsequently, the amine salt proceeded to ion-exchange with Na+-MMT. By respective incorporation of the different generations of dendrons onto layered MMT, the interlayer distance of the intercalated hybrid could be precisely controlled to form a unique structure with the possibility of self-assembly. Chromophore-containing dendrons (G1、G2 and G3) were utilized to intercalate layered silicates, resulting in a large d-spacings of different generations organoclays are 52Å, 133Å, and 85Å, respectively. After blending the organoclays with a high glass transition temperature polyimide (271 oC), respectively, the interactions between the hydrogen bond-rich dendrons and polyimide in the layered confinement resulted in ordered morphology, i.e. optical nonlinearity.

二次非線性光學有機高分子材&;#63934;具有比無機光學材&;#63934;&;#63745;大的分子設計自由&;#64001;、高的非線性光學係&;#63849;、高應答速度、低雷射損害、高分子質輕及易加工成膜,材&;#63934;取得&;#63845;宜…等優良特性。具備高光電係數、材料熱穩定性,為光電元件所必須。此外,如何避免高溫、高電場下之極化過程,以減低材料之昇華、裂化亦為一重要課題。本實驗利用具反應選擇性之構築單元(IPDA) 以收斂方法製備一末端具有發色團基(disperse red 1;DR1)之polyurethane/malonamide dendrons (G0.5~G3)。
研究首先利用IPDA中之-NCO官能基與 (DR1) 中之-OH 官能基進行加成反應產生urethane 鍵結之G0.5。之後,再將IPDA中之azetidine-2,4-dione 官能基與一級胺 (diethylenetriamine;DETA) 開環反應形成 malonamide 鍵結 (G1),反覆進行加成與開環步驟可得到高代數之樹枝狀分子,將各代數之樹枝狀分子進行結構鑑定。實驗並將具有二級胺結構之樹枝狀分子 (G1、G2、G3) 以離子交換方式將樹枝狀分子導入蒙脫土層板形成一有機黏土,其插層型態層間距分別為52 &;Aring;、133 &;Aring;及85 &;Aring;。之後將有機黏土與具高玻璃轉換溫度 (Tg = 271 oC) 、高成膜性之聚亞醯胺以10 wt%、20 wt%進行物理混摻形成具備自組裝排列之奈米複合材料,利用solvent casting方式製備具非中心對稱排列之光學薄膜。利用樹枝狀結構隨著代數成長具有明顯之阻隔效應 (site-isolation effect) 之因素,於高代數、高濃度之奈米複材下可減少聚集現象的產生,增加其非線性光學係數。
論文更進一步探討其自組裝之機制,將構築單元IPDA為核心與發色團基 (DR1) 製備出不同代數之樹枝狀有機黏土,與先前本實驗室以IDD為構築單元之樹枝狀有機黏土比較,探討其光電性質之差異。由實驗結果可知,雖然構築單元IDD之分子量較IPDA為構築單元來的大,但由於構築單元IPDA之結構 (-Ar-) 較IDD之結構 (-Ar-CH2-Ar-) 在分子排列上容易站立排列,因此導致其層間距較IDD系列來的大,且其光電係數值亦較IDD系列來的高,此合成更加證明樹枝狀結構對於自排效應之影響。
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