含巰基乙醇取代基與含各種不同硫醇取代基之聚苯胺的合成、性質鑑定與應用

林以中(Yi-Zhong Lin)

指導教授 ： 韓建中

國立清華大學/理學院/化學系/博士(2006年)

摘要

由CRS反應合成巰基乙醇取代聚苯胺共聚合物，在經由UV-vis、ESCA與ATRIR等儀器分析後，證實巰基乙醇確實被引進到聚苯胺高分子主鏈中，而非是巰基乙醇殘存於聚苯胺高分子鏈；而且其取代量正如原先所提出CRS反應機構所預測的一樣，將近有25 %左右；並由溶解度的測試證實了引進巰基乙醇取代基確實改變了其溶解的參數，使得此共聚合物可以溶解在原本聚苯胺所無法溶解的非溶劑中，如THF、2-methoxyethanol與di(ethylene glycol)等有機溶劑；同時仍然能保有不錯的導電度5~1.4 S/cm (巰基乙醇取代量由24~38 %)，這和一般文獻報導之poly(alkoxyaniline)s相比較，至少高出了將近三個級數以上，因此證明了CRS反應在和傳統苯胺分子引進側鏈取代基再氧化共聚合形成高分子的反應相比較，是屬於一種比較好的合成含側鏈取代基聚苯胺共聚合物之方法。
利用變溫實驗與加入D2O，我們確實可以確定巰基乙醇取代聚苯胺上-NH與-OH基的位置，同時也可以和ESCA結果相比對，證實巰基乙醇被引進於聚苯胺高分子主鏈中，並計算其取代量大約是在22~25 %附近。此外，根據文獻與二次取代巰基乙醇取代聚苯胺跟正丁烷基取代聚苯胺的 1H NMR結果，發現sulfoxide及氫鍵作用力的影響，會使其主要訊號峰往downfield的位置。最後利用變溫技術與model compound (trimer-SBu) 可以斷定有接上側鏈取代基苯環之ortho、meta與para氫的位置。
運用注入空氣的技術以及加入I2當Cu+的氧化劑，確實能用相當於催化劑量的CuCl2，於DMF溶劑系統中，在短時間內 (一小時) 將Pan (LB form) 迅速氧化成Pan (PB form)；而且利用其在DMF中溶解度的差異性，能得到高氧化態聚苯胺 (接近PB form) 的沈澱析出。而運用CRS方法引進正丁烷基硫醇於此高氧化態聚苯胺主鏈時，用的確獲得到取代量為43 % (有1~3%的誤差) 的正丁烷基硫醇取代聚苯胺，而且沒有發生交聯現象的情況。
如果硫醇碳鏈數在三個以下，其硫醇取代聚苯胺共聚合物的取代量均為24~25 %，正如本實驗室所提出之CRS反應理論架構。但是超過三個碳鏈以上，比如說正丁烷基硫醇，其ESCA量測的取代量 (即硫氮比) 就會超過25 %，而且隨著碳鏈數的增加，其取代量量測結果會越高；這可能是由於有二硫化物的產生，再加上碳鏈數越多其和硫醇取代基的凡得瓦力也會越強，因此導致其被包圍在高分子鏈中而不易移除。但是如果以適當的溶劑如NMP，將高碳鏈數的硫醇取代聚苯胺共聚合物溶解，此時二硫化物就會因高分子鏈溶解而脫離，因此量測其可溶與不可溶部分的取代量均為25 %，就如CRS反應所預測的一樣。此外藉由二次取代的反應，我們可以引進不同種類的硫醇於聚苯胺高分子主鏈中，使其能達到各種應用的需求。
在巰基乙醇取代聚苯胺的應用方面，利用其薄膜為載體，可以在常溫下與Ti(OBu)4生成顆粒小 (25 nm) 又是anatase狀態的TiO2，而適用於當光觸媒的材料；此外Pan-MEA也可以當作染料敏化型太陽能電池上的染料；亦可以形成所謂的微胞結構 (大小在116 nm) 來當作許多奈米顆粒生成的模版。因此可以看到巰基乙醇取代聚苯胺共聚合物具有相當大的應用範圍。
最後以正丁烷基硫醇取代聚苯胺共聚合物當作cathode/electrolyte，運用在鉭半導體電容器上，的確能得到很好的電容值 (理論最大電容值的99 %)，表示在鉭電容器的研究上，以CRS方法合成的硫醇取代聚苯胺共聚合物的確具有其應用的價值。雖然在DF值與ESR值的研究方面，還不能達到商品化的目標，但是由於知道其問題可能發生的原因，將來我們將改變浸泡的方式與適當的清潔步驟，並採用更好的摻雜方式，來降低其DF與ESR值，並往商品化的方向邁進。

關鍵字

聚苯胺 ； 巰基乙醇 ； 聚苯胺衍生物 ； 同步還原與取代反應

並列摘要

We can synthesize Pan-MEA via concurrent reduction and substitution reaction (CRS). After the instrumental analyses, we can confirm that 2-mecaptoehanol (MEA) is truly introduced into the polymer backbone, but the residue in the polymer. Moreover its substitution degree is nearly 25 % as the CRS reaction mechanism originally proposed. And with the solubility test, we find the introduction of MEA substituting group truly changes its dissolved parameter, and it could be dissolved in the organic solvent which polyaniline is unable to dissolve originally, like THF, 2-methoxyethanol and di(ethylene glycol) and so on. It also could have good conductivity about 1.4~5 S/cm (the substitution degree is 24~38 %). Compared to the other literature reports, the conductivity of Pan-MEA is at least higher than the poly(alkoxyaniline)s about three orders. Therefore the CRS reaction is proved as a better method compared to the traditional oxidative polymerization.
Using the temperature-changed technique and adding D2O, we define the -NH and -OH group position of Pan-MEA. From the 1H NMR results, we can calculate its substitution degree is about 22~25 % and the same as the ESCA results. In addition, according to the literature and the 1H NMR result of Pan-MEA and Pan-SBu (Pan-SC4H9), we discover that the influence of sulfoxide and hydrogen bonding can cause splits from its main signal peak toward the downfield position. Finally according to the temperature-changed and trimer-SBu 1H NMR results, we could conclude the ortho、meta and para hydrogen position when benzene ring has the substituted group.
Using the method of air bubbling and adding I2, we can oxidize Pan (LB form) to Pan (PB form) in short time (1 hour) with catalytic amount of CuCl2 in the DMF solvent system. Moreover using the solubility difference in DMF, we can obtain high oxidation state polyaniline (almost PB form) powder. When we introduce 1-butabethiol to the polyaniline via the CRS reaction, the substitution degree is 43% (1~3% error), and no crosslinking phenomenon occurs.
If the carbon chain number of thiol is below three, the substitution degree of polyaniline copolymer is 24~25 %, just as the CRS theory predicts. But when above three, for example 1-butanethiol, the substitution degree of Pan-SBu measured with ESCA will be over 25 %. The more the carbon chain number is, the more the substitution degree. This is possibly because the polyaniline copolymer has disulfide side product in the polymer backbone. When the carbon chain number increases, the van der Waals force will also become stronger; therefore it will cause disulfide surrounded in the polymer is hard to removed. But when Pan-SBu is dissolved in NMP, the substitution degree of dissolved and non-dissolved Pan-SBu is 25 % because of the remove of disulfide. In addition, with the second time CRS reaction, we can introduce different types of thiol into the polyaniline chain, and increase its application.
Pan-MEA has many kinds of application, for example, it can be used in the production of TiO2 antase form nano-particle (25 nm); it also may be used as dye on the solar cell; in addition it can form the so-called micelle structure (size 116 nm) as the pattern plate of the production of nano-particles.
Finally we use Pan-SBu as cathode/electrolyte in the tantalum semiconductor capacitor, and indeed obtain very good capacity (99% of the maximum theory capacity), although the DF and ESR value still cannot achieve the commercialized goal. But we have known where the question is, and in the future we will choose the suitable clean step and select a better doping method to reduce its DF and ESR value, and will make great strides toward the commercialized direction.

參考文獻

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