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標題: Synthesis and Properties of Thermally Stable NLO Poly(amide imide) via Poly(acylurea) Intermediates
作者: 汪乙嘉
Wang, Yi-Jia
關鍵字: 非線性光學;聚醯胺-醯亞胺
出版社: 化學工程學系
Several important properties are required for the practical applications of nonlinear optical (NLO) polymers, including large optical nonlinearities, low optical loss and long-term stability. Over the past decade, there are many ways to prevent the randomization of the poled order, such as incorporating high glass transition temperature (Tg) polymers, creating polymer networks or developing organic/inorganic hybrid. These systems offered excellent stability, however, due to the restriction of high Tg and high crosslinked density matrices, these systems showed poor poling efficiency. In this study, we used polyacylurea as an intermediate to prepare thermally stable NLO materials with high poling efficiency. This intermediate exhibits high solubility, which enables the fabrication of high quality films. Moreover, its lower Tg characteristic allows this polymer to have high poling efficiency during the poling process. After in-situ poling and curing, the acylurea can be converted to a rigid amide-imide structure. The Tg will elevate significantly by this conversion process. E-O coefficients, r33 of approximately 4.7-25.2 pm/V and their temporal stability at 80 ℃ were obtained. In this study, not only the high poling efficiency can be obtained, but the temporal stability were also enhanced by the formation of amide-imide linkages as well.

有機高分子非線性光學材料,具較大的分子設計自由度,一般藉由分子的結構設計,再經過高電場的極化(Poling)步驟使發色團基呈非中心對稱排列(Noncentrosymmetric alignment),而得到較無機材料大之非線性光學係數。此類材料在光電元件應用上,熱穩定性為其極待改善的主題。一般藉由導入高玻璃轉移溫度(Tg)聚合物、網狀交鏈系統或無機網狀結構來改善其熱穩定性,然高玻璃轉移溫度及高交鏈密度會造成電場極化之排列效率降低。為了同時解決有機高分子非線性光學材料在高溫穩定性及極化排列效率的問題,本研究以Polyacylurea(PAC)中間體,具溶解度佳及成膜性良好之優點,配置成溶液,塗佈於ITO玻璃基材上,同時,利用即時接觸式極化(In-situ contact poling)裝置監測電光係數與所施加電壓之關係,如此可得到最適化之極化條件,並於極化同時,將Polyacylurea中間體轉變為高Tg之聚醯胺-醯亞胺高分子(PAI)。研究中成功合成出聚碳二醯胺(PCDI)、Polyacylurea和二次非線性光學聚醯胺-醯亞胺高分子(NLO-PAI)。而在二次非線性光學聚醯胺-醯亞胺高分子其熱性質方面,Td為265~355℃、Tg為150~210℃;電光係數值r33約4.7~25.2pm/V之間,且在80℃下100小時之長時間熱穩定性,仍能維持在75%以上。此一材料經由Prism coupler量測後,發現具有光波導之特性,在元件應用上極具潛力。
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