藍相液晶摻雜旋性聚合物之表面穩定效應之研究;Studies of surface stabilization effect based on chiral polymer-doped blue phase liquid crystals

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題名:	藍相液晶摻雜旋性聚合物之表面穩定效應之研究;Studies of surface stabilization effect based on chiral polymer-doped blue phase liquid crystals
作者:	陳亭惠;Chen,Ting-Hui
貢獻者:	光電科學與工程學系
關鍵詞:	藍相液晶;旋性聚合物;聚合物
日期:	2016-07-22
上傳時間:	2016-10-13 13:15:25 (UTC+8)
出版者:	國立中央大學
摘要:	藍相液晶存在溫度範圍與其對電壓的穩定性為藍相液晶在近年來受到相當重視的研究主題之一，因藍相態存在於膽固醇態與各向同性態之間的狹窄溫度範圍中，因此如何拓寬藍相液晶存在的溫度範圍顯得相當重要。西元 2002 年 H. Kikuchi 所發表的高分子穩定藍相液晶技術(Polymer-stabilized blue phase liquid crystals, 簡稱 PSBP-LCs)為目前最主要拓寬藍相液晶存在溫寬的方式[1]，而本論文有別於高分子聚合物穩定藍相液晶結構，利用旋性聚合物在藍相態與不同溫度的各向同性態下進行拓寬藍相液晶存在溫度範圍的測試。經實驗結果證實，旋性聚合物摻雜藍相液晶進行光聚合後亦可拓寬藍相液晶存在溫寬，為深入探討其機制，本論文以以下幾種不同變數分別進行討論：(1)旋性聚合物的摻雜濃度、(2)聚合物照光聚合過程的溫度、(3)聚合物照光聚合時間及(4)液晶盒厚度等。經由不同參數的改變，發現高濃度旋性聚合物摻雜的樣品在各向同性態下進行照光聚合後，依然能拓寬藍相存在的溫寬範圍，證明除了 PSBP-LCs 利用藍相液晶本身的缺陷線穩固藍相外，亦可用聚合物在基板表面上的結構穩固藍相，我們稱之為表面穩固效應(Surface-stabilized blue phase liquid crystals，簡稱 SSBP-LCs)。據文獻指出，一般聚合物僅能在溫寬極窄的藍相態下進行光聚合反應以拓寬藍相的溫寬，而摻雜旋性聚合物較能在不同溫度的各向同性態下進行寬溫比一般聚合物更簡單地拓寬藍相溫寬。最後，我們比較 SSBP-LCs 與 PSBP-LCs 將藍相存在溫度拓寬後其光電特性的差異，實驗證實，SSBP-LCs 所穩固的藍相液晶光電特性亦不亞於PSBP-LCs 所穩固的藍相液晶，也因少了聚合物在液晶盒內部之網絡結構的影響，故可提供更快速的反應速度。最後，依本論文所發現的現象提出SSBP-LCs 穩定藍相液晶的寬溫機制，相信此成果將對藍相液晶未來之技術發展有相當之助益。;Recently, the temperature range and stabilization of structures with the application of external voltages of blue phase liquid crystals (BP-LCs) have become two of the key research topics for BP-LCs. Both of them have been paying much attention significantly by scientists. Since the temperature range of BP-LCs is extremely narrow, it is clear that the extension of temperature range is one of the key points in BP-LCs field. Currently, polymer-stabilized BP-LCs (PSBP-LCs), reported by H. Kikuchi in 2002, becomes the most commonly used method to extend the temperature range of BP-LCs.[1] In this thesis, we do lots of experiments about chiral polymer-doped BP-LCs but not achiral polymer-doped BP-LCs. The reported stabilization of BP-LCs is based on the polymerization of chiral polymer at various temperature of LCs at blue and isotropic phases. According to the experimental results, the polymerized chiral polymer onto the substrates can be used to extend the temperature ranges of BP-LCs significantly. To elucidate the mechanism for extending the temperature ranges of BP-LCs, several factors for the processes of photo-polymerization are considered. They include (1) the concentrations of chiral polymer; (2) the temperatures of LCs (blue and isotropic phases) during photo-polymerization; (3) the UV-curing durations; (4) the cell gaps, and others. It turns out that the temperature ranges of BP-LCs can be extended by the polymerized chiral polymer of 6 wt% by UV illumination at isotropic phase. The mechanism of extending the temperature ranges of BP-LCs by chiral polymer-doped BP-LCs is based on the polymerized chiral polymer structures onto the substrates, which is different from that of PSBP-LCs. Such a stabilization approach is called “Surface-stabilized blue phase liquid crystals (SSBP-LCs)”. According to the references, PSBP-LCs can only be achieved by polymerizing the doped polymers at the temperature of blue phase, thus the processes for achieving SSBP-LCs is much easier than PSBP-LCs by polymerizing the doped chiral polymers at isotropic phases. Finally, we have also compared the electro-optical properties of SSBP-LCs with those of PSBP-LCs, and the results show that the properties of SSBP-LCs are as good as those of PSBP-LCs. Notably, the response time of SSBP-LCs is shorter than that of PSBP-LCs. Accordingly, we believe that such a novel approach can improve the development of BP-LCs in LC technology.
顯示於類別:	[光電科學研究所] 博碩士論文

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