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研究生： 王麗緹
wati, Linda
論文名稱： 含桂皮酸酯之光致變及熱致變性膽固醇液晶共聚高分子之合成及特性探討
Synthesis and Characterization of Photochromic and Thermochromic Cholesteric Liquid Crystalline Copolymers Based on Cinnamate Ester
指導教授： 劉瑞祥
Liu, Jui-Hsiang
學位類別： 碩士
Master
系所名稱： 工學院 - 化學工程學系
Department of Chemical Engineering
論文出版年： 2009
畢業學年度： 97
語文別： 英文
論文頁數： 86
中文關鍵詞： 膽固醇液晶 、光異構化 、熱變色性 、光變色性
外文關鍵詞： cholesteric, photoisomerization, thermochromic, photochromic
相關次數： 點閱：66  下載：3 
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    • 本研究中合成一系列具有不同末端基團之液晶單體及具光變色性不同液晶元結構之對掌性單體，並以不同比例進行自由基共聚合反應。利用FT-IR及1H-NMR鑑定各化合物的分子結構，以DSC、TGA及POM進行熱性質分析，並探討此新穎性高分子材料的熱及光學性質。所合成的共聚物皆表現出具有選擇性光反射的膽固醇液晶相，而含-OC4H9末端基團之共聚物則在較低溫度時可顯示層列型液晶相。共聚物中桂皮酸酯(Cinnamate)的光致變基團可藉由UV光的照射而進行E-Z光異構化行為，改變分子結構及其排列，進而影響膽固醇液晶相所表現的選擇性光反射。對於共聚物CP1和小分子液晶E7之混合薄膜所表現的選擇性光反射顏色可依不同混合比例、溫度及UV光照射來進行調變。結果顯示加熱及UV光照射皆會導致反射光波長的藍位移，此現象可歸因於分子螺旋排列的螺距及折射率變化所造成的影響。本研究所合成之熱變色及光變色性共聚物在溫度感測、溫度影像紀錄及光學資訊的不可逆紀錄等應用上具有潛力。

    A series of novel liquid crystalline monomers and copolymers with various terminal groups, mesogenic groups and molar ratios were synthesized and both thermal and optical properties were investigated. The chemical structures of the compounds were confirmed by FTIR and 1H-NMR. The mesomorphic properties and phase behaviors were investigated by differential scanning calorimetry, thermogravimetric analyses, and polarized optical microscopy. The copolymers with cyano group show cholesteric phases and the copolymers with butoxy group show smectic and cholesteric phases. Photochromic groups in copolymers contain a C=C double bond capable for undergoing E-Z isomerization during UV irradiation. All of the synthesized CP1 films with different weight ratio of E7 form a cholesteric phase displaying selective light reflection with various λmax depending on the concentration of chiral groups. Heating and UV light irradiation of mixtures lead to a shift of the selective light reflection peak to a short-wavelength spectral region (blue shift). This effect is ascribed to the variation of helical pitch and refractive indices of the mixtures during heating and UV light irradiation. The possible explanations of this phenomenon were suggested. These thermochromic and photochromic copolymers are expected to be use widely in the field of thermal sensing, thermal image recording and irreversible recording of optical information.

    Abstract I Contents III Table of Tables VI Table of Figures VII Table of Schemes X Chapter 1 Introduction 1 1.1 Preface 1 1.2 Research Motivation 3 Chapter 2 General Introduction and Theoretical Background 4 2.1 Liquid Crystal 4 2.1.1 Thermotropic Liquid Crystal 5 2.1.1.1 Nematic Liquid Crystal Phase 6 2.1.1.2 Smectic Liquid Crystal Phase 7 2.1.1.3 Chiral Nematic (Cholesteric) Liquid Crystal Phase 9 2.1.2 Lyotropic Liquid Crystal 10 2.2 Cholesteric Liquid Crystal 11 2.2.1 Selective Light Reflection 12 2.2.2 Applications 15 2.2.2.1 Liquid Crystal Thermometers 15 2.2.2.2 Optical Imaging 16 2.2.2.3 Non-destructive Testing [24] 16 2.2.2.4 Radiation Sensing 16 2.3 Liquid Crystalline Polymers 17 2.3.1 Main Chain Liquid Crytalline Polymers 18 2.3.2 Side Chain Liquid Crytalline Polymers 19 2.3.2.1 Effect of spacer length on mesomorphic behavior 20 2.3.2.2 Effect of mesogenic unit on mesomorphic behavior 20 2.3.2.3 Effect of polymer backbone on mesomorphic behavior 21 2.4 Photochromic Compound 22 2.4.1 Photochemistry of Cinnamates 24 Chapter 3 Experimental Section 27 3.1 Materials 27 3.2 Measurements 28 3.3 Synthesis of New Chiral Monomers 30 3.4 Synthesis of Monomers Containing Various Terminal Group 32 3.5 Copolymerization 34 Chapter 4 Results and Discussion 39 4.1 Monomers 39 4.1.1 Synthesis and Characterization of Monomers 40 4.1.2 Photochemistry of Photochromic Monomers in Solution 42 4.2 Copolymers 44 4.2.1 Synthesis and Characterization of Copolymers 44 4.2.2 Photochemistry of Copolymers in Solution 49 4.2.3 Optical Properties of Cholesteric LC Copolymers 49 4.2.4 Optical Properties of ChLC Copolymers and E7 Mixture 51 4.2.4.1 Thermal Effect 51 4.2.4.2 Weight Ratio Effect 52 4.2.4.3 UV Effect 52 Chapter 5 Conclusions 83 References 84

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