摘要
導電高分子如聚苯胺因具有獨特的光電性質而有廣泛的用途，在有機發光二極體及太陽能電池等應用方面，相關材料之電子能階（HOMO/LUMO）為影響元件效能的關鍵因素之一，關於聚苯胺的HOMO值，在文獻上僅有Heeger團隊利用特殊的hole-only LED元件，配合穿隧理論推算其HOMO能階約為4.8 eV。但因LED元件製備的複現性不易掌握且影響元件性能的參數眾多，故欲藉由此法取得可靠之數值，實非易事。一般研究是利用非水溶液之CV來推算共軛分子之HOMO與LUMO能階，但由於聚苯胺之結構特殊，具有無數多的不同氧化態，且文獻上關於聚苯胺非水溶液CV的研究結果，無論是氧化峰之數目或氧化電位值等皆不盡相同且眾說紛紜，關於其缺欠複現性之因，迄無定論。在此研究中，我們透過多種不同的方法和工具如CV、UV-vis、ATR-IR、XPS等重新探討聚苯胺在非水溶液中之CV行為，發現其與聚苯胺之起始氧化態有關，同時有建立了以CV精測其HOMO/LUMO值之可靠方法，結果顯示，不同起始氧化態之聚苯胺（由LB form至PB form）其HOMO/LUMO能階的確都不相同。此外，我們也因此建立了利用非水溶液電化學的方法取得穩定的完全氧化態之聚苯胺，並用來進行CRS反應，不僅可成功的製得約含50 %側鏈取代基之聚苯胺衍生物，且可證明其PB form之結構。
文獻報導之含側鏈取代基的聚苯胺，其往往會造成導電度大幅下降，一般文獻上皆歸因於其側鏈取代基之立體障礙或電子效應之影響。但近年來我們利用同步還原與取代反應（CRS）引進含硫烷之側鏈取代基的研究發現，真正造成導電度的下降與其主鏈的共軛缺陷結構有關。由於氟具有許多特殊性質（如最大之電負度，最小之原子半徑，高親油性質以及獨特之化學反應性等等），因此氟衍生聚苯胺應是一有趣的材料，但文獻上所報導之氟衍生聚苯胺具有高氧化電位、明顯藍位移之UV-vis吸收光譜、幾無氧化還原活性、及極差的導電度，且錯誤的將其皆歸咎於氟之強拉電子之效應。因此，我們欲利用同步還原與取代反應（CRS）方法合成氟衍生聚苯胺，以保有其主鏈之高共軛結構，用以探討氟取代基之真正電子效應。由一系列的實驗之結果證實，我們首次成功的利用CRS方法，以氟離子為親核試劑在適當的溶液中合成氟衍生聚苯胺。且亦成功的發展出多次重複進行CRS反應的方法，可因此合成一系列含有特定氟取代量之聚苯胺衍生物（F-Pan系列樣品）。此外，即使當其氟取代量高達100 mol%以上時，其導電度亦僅有些微之下降（~0.1 S/cm），且由UV-vis、IR、CV之研究結果，發現其皆可保有與非衍生聚苯胺一樣良好之氧化還原能力。反之，由氧化共聚合方法（OCP）所合成之含氟之聚苯胺共聚合物（Pan2F系列樣品）導電度極差（10-2~10-5 S/cm）、具有較高的氧化電位Eox1值與明顯藍位移的UV吸收光譜以及極差的氧化還原能力。經由上述的詳細比對的研究結果顯示，由CRS方法所合成之聚苯胺衍生物仍保有原先聚苯胺主鏈的規則性，而由OCP方法所合成之含氟之聚苯胺共聚合物，則在其主鏈上產生大量的1,3-linkage共軛缺陷結構，因而導致有效共軛長度大幅下降，這是造成其導電度下降的主要原因。此外，由CRS方法所得之F-Pan系列樣品，當氟取代量增加時，其CV之氧化電位不升反降，暗示著在此高共軛系統下，氟可透過其孤對電子進行共振回饋電子置主鏈上。為了驗證此論點，而NMR為一更理想且更直接之工具，可來檢驗其主鏈上電子密度的多寡及分布情況。因此，我們利用鈀金屬耦合反應合成一系列含氟苯胺寡聚物之模型分子（如PDA-F、PDA-3F、及pentamer-F），且透過各種NMR實驗技術（如1H NMR，13C NMR，1H-Homodecouple，NOE，HSQC，HMBC）來明確標定所有1H及13C的化學位移。結果顯示當氟嫁接到這些高共軛性之主鏈系統後，確實表現出非常明確的推電子效應，展現其特殊之電子效應。此外，我們發現在適當條件下，氟衍生聚苯胺可與不同之親核試劑進行置換反應，生成含醇基或烷基取代基之衍生聚苯胺。利用CRS方法將O或C系統的親核試劑直接取代到聚苯胺主鏈上此為文獻首例。故此論文之結果可大大擴展CRS反應之適用範圍，用來合成各種特殊之衍生聚苯胺。

Abstract
Owing to their novel electrooptical properties, conducting polymers like polyanilines (Pans) have been demonstrated to be particularly useful in many applications. Regarding to the applications in light-emitting diodes and solar cells, both HOMO and LUMO energy levels of the employed materials are the critical parameters for the performances of the devices. In literature, the HOMO level of polyaniline（Pan）has only been estimated once by Heeger et. al. as 4.8 eV via a rather complicated approach, i.e., based on a specially prepared hole-only LED device and in combination with the Fowler-Nordheim tunneling theory. Due to the enormous number of fabrication parameter, it is not easy to prepare the LED devices with reproducible quality. Hence, the HOMO level measured based on the LED device may not be sufficiently reliable. The HOMO and LUMO levels of conjugated molecule are often estimated from the on-set potential of the oxidation or reduction peak of its CV curve. However, the previous literature reports indicated that the redox behaviors of Pan in nonaqueous electrolytic solutions were very complicated and actually somewhat confusing. Different reports often showed different CV curve shapes having different number of oxidation peaks and values of oxidation potential. Such non-reproducible and irreversible electrochemical behaviors of Pan in nonaqueous solution were not yet fully understood up to now. Herein, we re-investigated the CV behaviors of Pan in nonaqueous electrolytic solutions in conjunction with ATR-IR, in-situ UV-Vis, and XPS studies. Interestingly, we found that the CV behaviors of Pan in nonaqueous electrolytic solutions are highly depending on its initial oxidation status of Pan. Based on such findings, we have developed a reliable method to estimate the HOMO/LUMO values of Pan. The study suggests that Pans of different initial oxidation states (from LB to PB form) should have different HOMO/LUMO values. Moreover, we have also developed a method to obtain a stable film of fully oxidized PB form of Pan, by which highly substituted Pan（~ 50 mol%）can be prepared via the CRS route. Such results were also useful in confirming the structure and properties of the PB form.
In literatures, substituted Pans have always been found to exhibit much lower conductivities than that of the unsubstituted Pan and the results had been attributed to the substituent’s steric hindrance effect (for R and OR) or electron withdrawing effect (for halogen). However, our previous study indicated that, based on the result of butylthio-substituted polyaniline obtained via the CRS route, the unusually low conductivity of alkyl- or alkoxy-substituted Pans is arisen from their backbone conjugation defects (e.g., 1,3-ring linkage structures) as induced by the substitutent group during the growth of the polymer chains. Because of the unusual properties associated with the fluorine atom, such as high electronegativity, small atomic radius, high lipophilicity, and unique chemical reactivity, the fluorinated-polyaniline should be highly interested. But all the previously reported poly(fluoroaniline)s prepared by the OCP method were found to have greatly increased oxidation potential, significantly blue-shifted UV-vis absorption, lack of redox activity, and much lower conductivity. Therefore, we decided to develop a feasible method for introducing the F-substituent to the preformed polyaniline backbones via the CRS method. Via this synthetic approach, the backbone structure of the fluorinated-polyanilines (F-Pans) could be maintained the same as the parent unsubstituted Pan, so that the electron effect of the substituent group could be fairly and reliably evaluated. We then have successfully synthesized a series of fluorinated-polyaniline（F-Pan）with controlled amounts of F-substituent. Surprisingly, the F-Pan samples prepared by the CRS method were found to be much highly conductive and electroactive than the Pan2F samples prepared from the OCP method. Even with a substitution degree of greater than 100 mol%, the obtained F-Pan showed only a slight decrease in its conductivity (~0.1 S/cm). Furthermore, the UV-vis, IR, and CV studies indicated that F-Pan have retained similar good redox activities as that of the unsubstituted Pan. On the other hand, the Pan2F samples prepared from conventional oxidative copolymerization（OCP）method were found to be pooly conductive (10-1~10-5 S/cm), with much higher oxidation potential Eox 1, significantly blue-shifted UV-vis absorptions, and extremely deactivated redox activity. The results of our thorough comparison studies indicated that the F-Pan samples prepared from the CRS method retained the same highly conjugated structure of the parent unsubstituted polyaniline, while Pan-2F samples prepared from the OCP method contained significant amounts of 1,3-linkage conjugation defects, which greatly shortened the effective conjugation extent of the backbone and dramatically reduced their conductivities. Furthermore, the CV results for the CRS-prepared F-Pan samples showed that, as the fluorination degree increased, its oxidation potential actually decreased and eventually became lower than its parent unsubstituted Pan. The results imply that the fluorine atoms on the highly conjugated polyaniline backbone may actually help to increase the electron density of the backbone through the resonance donation of their lone-pair electrons. To better understand the electronic behaviour of the F in the higher conjugated aniline systems, we have systhesized a series of conjugated aniline model compounds (PDA-F、PDA-3F、pentamer-F) and studied the compounds with various 1D and 2D NMR experiments (1H NMR、13C NMR、1H-homodecouple、NOE、HSQC、HMBC) to fully and unambiguously assign the chemical shifts for all the H and C of the compounds. The results clearly confirmed the resonance electron-donating effect of the fluorine atoms in these higher conjugated aniline systems. In addition, we found that the fluorine group in F-Pan can be replaced by other types of nucleophiles under some appropriate conditions to convert into the alkoxy- or alkyl-substituted Pans, which are otherwise very difficult to accomplish directly via the CRS method. Therefore, the results and findings of this dissertation can greatly expand the application scope of the CRS method for the preparation of various types of substituted-polyanilines.

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