導電高分子 (conjugated conductive polymers, CPs) 相關研究是近年來最受矚目的研究領域之一，可藉由改變摻雜程度來調控其導電度，側鏈鍵結不同的取代基其性質也不同，因此被廣泛應用於各個領域，在眾多種類的高分子之中，又以聚噻吩具有高導電性、易合成、及熱穩定性等優點，使得聚噻吩及其衍生物或是擁有類似結構的共軛高分子最引起學者們的關注。
　　本篇論文針對噻吩單體的二號位進行修飾，並以本實驗室所開發之質子酸
(Brønsted acid) 酸催化聚合法進行聚合反應，透過引入不同鹵素離去基 (F, Cl,
Br, I)，來探討鹵素離去基對聚合反應的活性，並對其導電度、共聚合模式進行探討，提升噻吩的加工性及應用價值。
　　雖然在合成二號位氟離去基時，起始物與產物極性相近不易分離，未得到純的氟化產物。但是有別於使用正丁基鋰搭配NFSI氟化試劑的方法，成功設計出新的合成策略，不僅處理上方便且更加安全。其餘鹵素離去基 (Cl、Br、I) 皆已找到良好的合成條件 (反應時間約一小時，產率高達九成)。
　　酸催化聚合關鍵離去基為氟時，不含氟噻吩單體會抑制高分子鏈成長。若能提高含氟單體純度，將會是個極具潛力的單體 (HF不易斷鍵，不僅能提高反應速率，還不會使PDI數值上升)；離去基為氯時，雖然反應時間過長，但是平均分子量、最大吸收波長皆明顯高於其餘三種鹵素離去基；離去基為溴時，由於反應中會釋放HBr而導致啟動更多單體、產生大量短鏈高分子，造成PDI值極大，然而其產率是四者之中最高；離去基為碘時，因為碳-碘鍵能為四種鹵素離去基中最小，故碘相當容易離去形成二聚體，高分子產率明顯下降。若能善用不同單體的聚合特性，透過共聚合的方式來改善各自不足的地方，將能提高其應用性。

　　Conjugated conductive polymer attracts much attention in these years due to its unique physical properties. The conductivity and solubility of polymer can be controlled by adjusting its doping level and modifying its side chain. Among these kinds of polymers, polythiophenes hold the advantages of high thermal stability, excellent conductivity, and flexible processability.
　　This thesis focused on the influence of the leaving groups (e.g. F, Cl, Br, I) on the acid-catalyzed polymerization of polythiophene. By using thiophenes containing different halides as the leaving groups, we have studied the effect of the leaving groups to the acid-catalyzed polymerization. Furthermore, to expand the application and processability of polythiophenes, we investigate their conductivity and conduct the copolymerization.
　　Although the synthesis of pure 2-fluorothiophene was difficult, we still successfully develop a new synthetic strategy compared to other method employing n-BuLi as the key reagent. Thiophenes containing other leaving groups such as Cl, Br, and I have been synthesized in good yields in rather short reaction time.
　　In the case of 2-fluoro-3-butoxythiophene, the non-fluorinated thiophene impurity will suppress the polymerization. However, if we could increase the purity of 2-fluorothiophene, it would be an ideal monomer for the acid-catalyzed polymerization. Because HF is easy to undergo elimination, and the PDI can be maintained in a reasonable narrow range. In the chlorine case, even though it takes much longer reaction time, the polymer reveals better molecular weight and UV absorption. During the polymerization, 2-bromothiophene will release a strong acid, HBr, and is hard to get low PDI, but it can achieve the best yield among all cases. The bond energy of C-I is relatively low, so it’s easy to form dimer which can suppress the yield.
　　Modifying the properties of different leaving groups can help us to solve the possible problem in the acid-catalyzed polymerization of polythiophene and enhance its processability and application.

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