臺灣博碩士論文加值系統

誘電性液晶具有快速應答、廣視角、雙安定性、自發偶極與記憶性等優良的光學性質，但是誘電性液晶在顯示器的應用上，由於誘電性液晶需要使用表面安定技術（試片厚度小於2μm）將之解旋後方能達到最佳的光電效果，過於薄的試片厚度導致在大尺寸誘電性液晶顯示器製作時良率不佳，造成目前此種液晶材料的開發受到限制，因此如何建立一全新誘電性液晶排列之機制，且將之應用於間隙較厚之液晶元件上並仍具優良之光電性質即成為重要之課題。
本研究為誘電性液晶的缺點，改善誘電性液晶排列上之問題，故採用賓主系統並結合原位聚合法與光誘導排列法，利用分子設計合成出三系列共九個同時具有丙烯酸酯基與肉桂團基化合物。結構包括以長碳烷基為間距（其碳數n為8, 10, 12），液晶基為苯及聯苯，連接基為丙烯酸酯，末端不對稱基為含0~2個不對稱中心以及五個碳原子長的烷基鏈，以壓克力為高分子主鏈，肉桂團基為交聯基。
研究共分為三大部份
第一部份為含有壓克力與桂皮團基化合物的合成與熱性質探討。合成三系列如前述結構之側鏈高分子單體；液晶相行為經由熱微差掃描卡計、偏光顯微鏡以及粉末X-ray繞射加以鑑定液晶相的種類與排列結構，分別探討不同間距長度以及末端不對稱基對液晶行為之影響。結果顯示，所有的化合物中，除柔軟間距過短及缺乏不對稱中心之ACI812N及ACI1012N沒有液晶相，當增加末端基之不對稱中心個數與偶極矩時，其結晶點的溫度有下降之趨勢，而增廣其層列型液晶相之溫度範圍，在雙不對稱末端基的液晶分子中，可增加SC*相之熱安定性，溫度範圍可達約50℃且包含室溫。
第二部份為賓主型系統的排列特性之探討。將第一部份所合成之單體進行二步驟之光化學反應，可得側鏈型高分子以及交聯其肉桂團基。第一步驟是利用波長365nm的紫外光照射聚合；第二步驟是透過波長313nm的線性偏極紫外光曝照而得。並針對側鏈交聯高分子對賓主型液晶系統的排列行為加以討論。結果顯示，高秩序度之側鏈交聯型高分子，能誘導液晶分子垂直於線性偏極光之方向排列。
第三部份為賓主型系統的光電特性之探討。選擇具有寬廣SC*相之誘電性液晶（MD312C）作為主液晶，而以第一部份所合成之單體作為其賓液晶。賓主型液晶系統測量自發性極化量、應答時間及對比度等光電性質。並探討側鏈高分子之交聯密度對其光電性質的影響。結果顯示，在不減慢其應答速度下，高秩序度之側鏈交聯可增加自發極化量約10%左右、對比度約100%左右。
本研究已成功的合成出可光聚合及光交聯之化合物，透過高秩序度之側鏈交聯型賓主系統，在不影響誘電性液晶應答速度之情況下，增加其排列性質、自發極化量及對比度，提供一全新的誘導排列機制。

Ferroelectric liquid crystals (FLCs) have great electro-optical properties of fast response time (τ), large spontaneous polarization (Ps) value, high contrast ratio (gray-scale), wide view angle, bistable character, and memory effect. However, the drawbacks of FLC materials such as thin cell gap are impeded the application of display and other uses of electro-optical devices.
In this work, we combine the advantages of guest-host system, in situ polymerization, and photoinduced reorientation to improve the drawbacks of FLCs. The monomers containing with acrylate and cinnamste groups were synthesized.
The liquid crystal (LC) thermal properties were characterized by differential scanning calorimetry, optical polarizing microscopy, temperature-dependent power X-ray diffraction measurements. The detailed relationships between chemical structures and liquid crystalline behaviors were discussed. In the results, it shows that all of the compounds have LC behaviors, except ACI812N and ACI1012N. As the dipole moment of tails increases, the crystalline point decreases, then widen the range of smectic phase. In the case of two chiral centers, the SC* phase can be achieved about 50℃ (including room temperature).
In the guest-host system, photoinduced reorientation can be achieved by ordered cross-type network via irradiated with 313nm linearly polarized ultraviolet light (LP-UV light). The ordered cross-type network can improve the electro-optical properties (higher spontaneous polarization value, constant response time, and higher contrast ratio) of the guest-host system. Furthermore, the cell gape of FLC display can be up to 5μm (potentially larger than 5μm). Upon irradiation, theses mixture-filled 5μm cells exhibit similar electro-optical properties as compared to those in the 2μm cells.

中文摘要 …………………………………………………… i
英文摘要 …………………………………………………… iii
誌謝 …………………………………………………… v
目錄 …………………………………………………… vi
List of Schemes …………………………………………………… viii
List of Tables …………………………………………………… ix
List of Figures …………………………………………………… x
第一章 緒論……………………………………………… 1
1-1 前言……………………………………………… 1
1-2 液晶介紹………………………………………… 2
1-2.1 液晶由來………………………………………… 2
1-2.2 何為液晶………………………………………… 2
1-2.3 液晶分類………………………………………… 3
1-3 依照液晶分子排列分類………………………… 3
1-3.1 向列型液晶……………………………………… 4
1-3.2 膽固醇液晶……………………………………… 4
1-3.3 層列型液晶……………………………………… 5
1-3.4 層列A型液晶相………………………………… 5
1-3.5 層列C型液晶相………………………………… 6
1-3.6 層列B型液晶相………………………………… 7
1-3.7 層列E型液晶相………………………………… 8
1-4 具有光學活性之層列型液晶…………………… 8
1-5 液晶高分子……………………………………… 11
1-6 側鏈型液晶高分子……………………………… 11
第二章 文獻回顧與研究動機…………………………… 13
2-1 誘電性液晶之沿革……………………………… 13
2-1.1 間距……………………………………………… 15
2-1.2 液晶基…………………………………………… 15
2-1.3 連接基…………………………………………… 16
2-1.4 末端基…………………………………………… 17
2-2 側鏈型誘電液晶高分子………………………… 19
2-3 自發誘電性電場極化現象……………………… 20
2-4 誘電性液晶的光電效應………………………… 22
2-5 表面安定型誘電性液晶………………………… 23
2-6 Z字型缺陷……………………………………… 25
2-7 光配向模擬……………………………………… 27
2-8 原位聚合高分子………………………………… 30
2-9 研究動機與實驗設計…………………………… 31
第三章 實驗部分………………………………………… 34
3-1 試藥……………………………………………… 35
3-2 結構鑑定儀器…………………………………… 35
3-3 液晶相鑑定與熱性質分析……………………… 36
3-4 液晶單體的合成………………………………… 38
3-4.1 肉桂酸間距之合成……………………………… 38
3-4.2 末端基之合成…………………………………… 42
3-4.3 液晶單體之合成………………………………… 43
3-5 液晶單體聚合度以及分子量之量測…………… 47
3-6 光誘導排列之測量……………………………… 47
3-7 液晶光電性質測試……………………………… 48
3-8 光電參數量測…………………………………… 50
第四章 結果與討論……………………………………… 54
4-1 液晶單體的化學結構鑑定及熱性質…………… 55
4-1.1 ACI812系列之化合物…………..……………… 55
4-1.2 ACI1012系列之化合物……………………….... 67
4-1.3 ACI1212系列之化合物………………………… 74
4-1.4 間距對液晶性質的影響………………………… 83
4-2 液晶高分子的聚合及光排列性………………… 85
4-2.1 液晶單體聚合度的研究………………………… 86
4-2.2 交聯密度對液晶之排列特性…………………… 87
4-3 液晶元件之測試探討…………………………… 90
4-3.1 自發性極化量之量測…………………………… 92
4-3.2 應答時間之量測………………………………… 98
4-3.3 對比度之量測…………………………………… 101
第五章 結論……………………………………………… 104
參考文獻 …………………………………………………… 106

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