Synthesis of thiophene-containing chiral inducers and preparation of the helical polymer by using electropolymerization in liquid crystal medium

摘要 在本篇論文中，我們合成了一系列含有噻吩的液晶摻混劑分子。利用偏光顯微鏡觀察摻混在液晶5CB中膽固醇相的生成，以及螺旋扭轉力(helical twisting power, HTP)的變化並探討其構型。在循環伏安法的測量中發現此系列分子的氧化電聚能力會隨著噻吩的數目增加，並利用紫外光吸收光譜，圓二色光譜(circular dichroism, CD)測量其光學性質與掌性結構，發現紫外光吸收峰會隨著噻吩變多逐漸紅移，而其CD吸收產生的Cotton effect逐漸變大，顯示構型逐漸固定。使用含三噻吩液晶摻混劑分子與三噻吩在液晶電解液中，施加不同偏壓進行共聚，測定電聚膜的CD光譜，發現非常大的偏光訊號。我們又分別在溶液中、液晶向列相、膽固醇相中進行電聚，發現含三噻吩液晶摻混劑分子本身產生的訊號跟螺距無關，而與三噻吩加長的噻吩鏈會產生另一組沿著液晶螺旋聚合的CD訊號，而在溶液中製作之電聚膜，沒有任何偏光訊號的產生。根據文獻報導，此系列分子可以進一步利用氧化電洞注入消除噻吩鏈沿著液晶螺旋聚合的CD訊號，留下另一組本身與液晶無關的訊號，此方法可製作出一電致變色偏光元件，其偏光訊號不隨變色而消失。Abstract A new type of copolymer, which combines terthiophene with the adding terthiophene-functionalized L-threitol-based chiral center, is prepared by electropolymerization in the liquid crystal medium. As the chiral center involving in the polyterthiophene, the polymer chain becomes twisted; therefore, shows very strong light-polarized property. During electrochroism redox process, the copolymer preserves mostly the light-polarized property with the function of changing color, which could be further used into advanced materials