含醯胺連結基之新型旋光性液晶材料的合成與光電性質的探討

Synthesis and Properties of Novel Chiral Liquid Crystal Materials with Amide Linkage Group

楊子良(Zih-Liang Yang)

指導教授 ： 吳勛隆

大同大學/工程學院/化學工程學系所/碩士(2004年)

摘要

本次研究的主要目的是嘗試闡明在旋光性液晶材料中結構與性質之間的關係。合成四系列同樣具有醯胺連結基之旋光性液晶材料，來探討改變非旋光烷鏈的長度（n）、不同的連結基種類（RO-，RCOO-）、以及旋光烷鏈的種類對於液晶相及其物性的影響。
液晶材料的液晶相及相變化的溫度是由偏光顯微鏡、DSC及光電量測來鑑定，而反誘電性液晶相(SmCA*)則是經由偏光顯微鏡的光學紋理圖、電流轉換行為、及光電應答行為來確定。
化合物DEnPBNPA (n=7~11, Z=COO) 在降溫過程中都可以觀察到Iso-SmA*-SmCA*-Cr的相轉移順序。所有的產物都具有enantiotropic 的SmA*液晶相，但在碳數為7、9時存在著enantiotropic 的SmCA*液晶相，碳數為8、10、11時則為monotropic 的SmCA*液晶相。
化合物DPnPBNPA (n=7~11, Z=COO) 在降溫過程中可以觀察到Iso-SmA*-Cr的相轉移順序。而DPnPBNPA (n=7~11, Z=COO)都具有enantiotropic的SmA*液晶相，且除了化合物DPnPBNPA (n=11, Z=COO)之外，隨著非旋光烷鏈長度的增加，Iso-SmA* 及SmA*-Cr的相轉移溫度減少。而Iso-SmA*的相轉移溫度則隨著隨著非旋光烷鏈長度的增加而有奇偶現像的產生。
化合物MPnPBNPA (n=7~11, Z=COO) 在降溫過程中可以觀察到Iso-SmA*-Cr的相轉移順序。而MPnPBNPA (n=7~11, Z=COO)皆存在enantiotropic的SmA*液晶相，且除了化合物MPnPBNPA (n=11, Z=COO)之外，隨著非旋光烷鏈長度的增加，Iso-SmA* 及SmA*-Cr的相轉移溫度減少。而Iso-SmA*的相轉移溫度則隨著隨著非旋光烷鏈長度的增加而有奇偶現像的產生。
化合物MPnPBNPA (n=10~14, Z=O) 在降溫過程中可以觀察到Iso-SmA*-SmCA*-Cr的相轉移順序。MPnPBNPA (n=10~14, Z=O)皆為monotropic的SmCA*液晶相，且隨著非旋光烷鏈長度的增加，SmA*的溫度範圍減少。當非旋光烷鏈長度從n=10到n=11時，SmCA* 的溫度範圍增加，而當非旋光烷鏈長度從n=12到n=14時，SmCA* 的溫度範圍逐漸減少。
化合物DEnPBNPA (n=7~11, Z=COO)的自發性極化值的最大值介於178~240 nC/cm2，而其傾斜角則介於16~19°；而化合物MPnPBNPA (n=11~13, Z=O) 的自發性極化值的最大值介於160~222 nC/cm2，其傾斜角則介於26~30°。兩系列的液晶材料經由光電應答行為的量測，在SmCA* 時皆呈現一典型反誘電性液晶材料的雙遲滯的光電應答行為。

關鍵字

反誘電性液晶材料 ； 旋光性液晶材料

並列摘要

The purpose of this research work was an attempt to the structure-property correlation in the chiral liquid crystal materials. Four series chiral liquid crystal materials which have an amide linkage were designed and synthesized in order to investigate the effect of the nonchiral peripheral chain length, n, the effect of different linkage group (RCOO- and RO-) and the effect of the different tailed structure on the mesomorphic properties.
The mesophase and their corresponding transition temperatures of the liquid crystal materials were identified by the polarizing microscopic texture, DSC carlorimetry and the electro-optical measurements. The antiferroelectric phase was further characterized by the polarizing microscopic texture, the switching current behavior and the electro-optical response.
The compounds of DEnPBNPA (n=7~11, Z=COO) exhibit a phase sequence of Iso-SmA*-SmCA*-Cr in cooling process. All compounds of DEnPBNPA(n=7~11, Z=COO) exhibit the enantiotropic SmA* phase, compounds of DEnPBNPA(n=7, 9, Z=COO) exhibit the enantiotropic SmCA* phase and the compounds of DEnPBNPA(n=8,10,11, Z=COO) exhibit the monotropic SmCA* phase.
The compounds of DPnPBNPA (n=7~11, Z=COO) exhibit a phase sequence of Iso-SmA*-Cr in cooling process. All compounds of DPnPBNPA (n=7~11, Z=COO) exhibit the enantiotropic SmA* phase. Expect for the compound, DPnPBNPA (n=11, Z=COO), the transition temperature of Iso-SmA* and SmA*-Cr decrease with increasing the aliphatic chain length. And the transition temperature of Iso-SmA* of compounds, DPnPBNPA (n=7~11, Z=COO) appear an odd-even effect.
The compounds of MPnPBNPA (n=7~11, Z=COO) exhibit a phase sequence of Iso-SmA*-Cr in cooling process. All compounds of MPnPBNPA (n=7~11, Z=COO) exhibit the enantiotropic SmA* phase. The transition temperature of Iso-SmA* of compounds, MPnPBNPA (n=7~11, Z=COO) appear an odd-even effect.
The compounds of MPnPBNPA (n=10~14, Z=O) exhibit a phase sequence of Iso-SmA*-SmCA*-Cr in cooling process. The compounds of MPnPBNPA (n=10~14, Z=O) exhibit the monotropic SmCA* phase. The temperature range of SmA* decreases with increasing the aliphatic chain length. The temperature range of SmCA* phase increases form n=10 to n=11 and then decreases from n=12 to n=14.
The maximum Ps values of compounds, DEnPBNPA (n=7~11, Z=COO) are in a range of 178~240nC/cm2 and the maximum tilt angles are in a range of 16° ~19°. The maximum Ps value of compounds, MPnPBNPA (n=11~13, Z=O) are in a range of 160 ~ 222nC/cm2 and the maximum tilt angles are in a range of 26° ~30°. These two series compounds display an ideal double hysteresis loop in SmCA* phase.

並列關鍵字

antiferroelectric ； chiral liquid crystal material

參考文獻

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