合成具磺酸基團之電活性聚醯胺酸與聚亞醯胺及其在電化學感測抗壞血酸與金屬防腐蝕之應用研究

Application studies of sulfonated electroactive poly(amic acid) and corresponding polyimide applied in electrochemical sensing of ascorbic acid and corrosion protection

黃湘媛(Hsiang-Yuan Huang)

指導教授 ： 葉瑞銘

中原大學/理學院/化學研究所/碩士(2018年)

https://doi.org/10.6840/cycu201800590

摘要

本碩士論文的研究主軸在探討自行合成之磺酸化電活性聚醯胺酸及聚亞醯胺及其在作為偵測抗壞血酸材料與防腐蝕塗料上的應用效果。 首先，使用自行合成之電活性具磺酸基團苯胺三聚體(sulfonated amino-capped aniline trimer，S-ACAT)，與市售二酸酐單體4,4’-(4,4’-Isopr-opyliden-ed-iphenoxy)bis(phthalic anhy-dride) (BPADA)，利用共聚合之方式，製備成具磺酸基團之電活性聚醯胺酸(sulfonated electroactive trimer polyamic acid，SEPAA)，接著再利用兩種脫水閉環縮合方式，分別為(1)化學縮合與(2)高溫縮合法，製備成具磺酸基團電活性聚亞醯胺(sulfonated electroactive trimer polyimide，SEPI)，因磺酸基團及具醯胺酸結構上之羧酸基團，皆為共振結構之基團，預期可有效提升整體材料之電活性，提高材料之應用特性。
第一部分之應用研究，為對抗壞血酸之偵測能力進行研究探討。為了證明磺酸基團可有效提升材料之電活性，因此製備無磺酸基團之苯胺三聚體(amino-capped aniline trimer，ACAT)當作對照組，與二酸酐單體BPADA，共聚合成電活性聚醯胺酸(electroactive poly(amic acid)，EPAA)，接著再利用化學縮合法，脫水閉環聚縮合後，製備成電活性聚亞醯胺(electroactive polyimide，EPI)，與SEPAA及同樣利用化學縮合法製備之SEPI，對磺酸基團及羧酸基團是否影響材料整體電活性之能力，進行比較性之研究。從FT-IR、1H-NMR、MS的圖譜可和文獻比對，證實成功合成出單體ACAT及S-ACAT，而EPAA、EPI、SEPAA及SEPI則由FT-IR進行結構鑑定。 接著經由循環伏安儀(Cyclic Voltammetry，CV)測試，可發現S-ACAT的電活性為ACAT的2.94倍，證實增加磺酸根的共振結構可增強其電活性。接著比較EPAA、EPI、SEPAA及SEPI這四種材料之電活性，由CV可證實，聚醯胺酸之電活性確實大於聚亞醯胺，表示羧酸基團確實可提升電活性，且一個磺酸基團所提升的電活性效益，約為羧酸基團之兩倍。以上四種電活性高分子材料對於抗壞血酸之偵測能力，可從電催化能力及電流應答實驗數據得知，其中對抗壞血酸偵測能力最為靈敏的為SEPAA，此乃由於SEPAA的結構，比偵測能力最差之EPI多兩個羧酸基團及一個磺酸基團，可證實結構中具有越多的共振基團，即可增強材料之電荷密度及電活性能力。
第二部分為金屬防腐蝕效益應用研究探討，本部分所使用之材料為，經由高溫熱縮合法閉環之EPI及SEPI，並利用市售二胺單體4,4'-Oxydianiline (ODA)，與BPADA共聚後同樣利用高溫熱縮法，製備成非電活性聚亞醯胺(non-electroactive polyimide，NEPI)，當作對照組進行比較性研究，但由於單純使用S-ACAT二胺單體與BPADA利用熱縮合法製備之聚亞醯胺薄膜易碎裂，無法作為後續應用，為克服這個問題，本論文採用兩種二胺單體ACAT及S-ACAT，以S-ACAT佔二胺單體莫爾比之(5 %及10 %)製備成SEPI-5及SEPI-10。首先利用ATR-IR對NEPI、EPI、SEPI-5及SEPI-10材料之結構進行鑑定，接著利用CV分別對以上四種聚亞醯胺材料進行電活性探討，結果與第一部分相同，具磺酸基團之聚亞醯胺有較高之電活性，且隨著S-ACAT添加比例越多有較高之趨勢。最後在電化學腐蝕的量測方面，將所製備之聚亞醯胺薄膜，利用各別高分子液當作黏合劑，將聚亞醯胺膜黏合於冷軋鋼片(cold rolled steel，CRS)上，製備成工作電極，以標準電化學腐蝕量測法，量測塔伏(Tafel)曲線及電化學阻抗(Impedance)，測試所製備之聚亞醯胺薄膜對金屬防腐蝕的能力。 由塔伏曲線發現，所合成之SEPI-10具最好的防蝕能力。 接著再由電化學阻抗測得的奈奎斯特圖(Nyquist plot)及伯德圖(Bode plot)亦發現同樣的趨勢，兩圖譜都再次證實了SEPI-10具有最佳的防蝕效果。 此部分之所以有較佳之金屬防蝕效益為，電催化能力可促使下方接觸的金屬表面(如: Fe)產生緻密的鈍性金屬氧化層(如: Fe2O3及Fe3O4)，此現象以拉曼光譜(Raman)光譜證實，其中以SEPI-10所產生的鈍性金屬氧化層，拉曼特徵峰值最為明顯。

關鍵字

磺酸 ； 羧酸 ； 聚醯胺酸 ； 聚亞醯胺 ； 抗壞血酸 ； 金屬防腐蝕

並列摘要

In this dissertation, a sulfonated electroactive poly(amic acid) and polyimide was first prepared, characterized and applied in sensing of ascorbic acid and anticorrosion. First, a sulfonated amino-capped aniline trimer (S-ACAT) and 4,4’-(4,4’-Isopr-opyliden-ed-iphenoxy) bis(phthalic anhy-dride) (BPADA) is prepared as a sulfonated electroactive poly(amic acid) (SEPAA) by copolymerization. Subsequently, sulfonated electroactive polyimides (SEPI) was prepared by two methods (i.e., chemical condensation and thermal condensation). It should be noted that the appearance of sulfonated group and carboxylic group was found to enhance the redox capability of electroactive poly(amic acid) and electroactive polyimide based on the electrochemical cyclic voltammetry. Enhancement of redox capability of as-prepared materials induced from sulfonated group and carboxylic group may promote the potential application in electrochemical sensing of ascorbic acid and anticorrosion of metal substrate.
The first part of this application research is to detect the sensing ability of SEPAA and SEPI. Amino-capped aniline trimer (ACAT) was also prepared as a control experiment and copolymerized with BPADA to synthesize EPAA, and followed by chemical condensation dehydration to prepared EPI, and the way to prepared SEPAA and SEPI are also with the same method as mention above. A comparative study was performed on the ability to enhance the electroactive of the material between sulfonated group and carboxylic acid group. The characterization of ACAT and S-ACAT was confirmed by the spectra of FT-IR, 1H-NMR, and MS. Moreover, the characterization of EPAA, EPI, SEPAA and SEPI were also identified by FT-IR spectroscopy. For the redox capability studies, S-ACAT was found to be 2.94 times that of ACAT based on the electrochemical cyclic voltammetry (CV) studies, implying the incorporation of sulfonated group into ACAT may promote the redox capability. On the other hand, If compared EPAA to EPI (or compared SEPAA to SEPI), the electroactive poly(amic acid) was always found to exhibit higher redox capability than that of EPI, indicating that carboxylic group can also promote the electro-activity of electroactive material. For the electrochemical sensing studies of AA, SEPAA was found to exhibit the highest sensitivity among all testing materials. This may be due to SEPAA containing two carboxylic groups and one sulfonated group as compared to that of EPI showing worst detection capability.
The second part of this application research is the corrosion protection of metal substrate. The materials used in this part are EPI and SEPI that are prepared by thermal imidization. The control experiment of non-electroactive polyimide (NEPI) was also prepared by commercial diamine monomer of 4,4'-Oxydianiline (ODA) with BPADA. However, polyimide films prepared from reaction between S-ACAT and BPADA are fragile easily and therefore cannot be used as in following application. Therefore, electroactive co-polyimide prepared from two diamine monomers, ACAT and S-ACAT, are reacted with BPADA. For example, with molar ratios (5% and 10%) of S-ACAT with respect to ACAT were denoted by SEPI-5 and SEPI-10. First, the structures of NEPI, EPI, SEPI-5 and SEPI-10 materials were identified by ATR-IR, Subsequently, CV was used to investigate the electroactivity of above four kinds of polyimide materials. For the electrochemical corrosion measurements, the electroactive copolymers were casting onto the cold rolled steel (CRS) electrode. It should be noted that SEPI-10 was found to reveal the best anticorrosion performance based on the electrochemical Tafel curve. Moreover, the same trend was also found in Nyquist and Bode plots. The possible reason for the best anticorrosion performance of SEPI-10 may be attributed to the best redox capability can promote the formation of densely passive metal oxide layer (such as: Fe2O3 and Fe3O4) on the surface of the metal (such as: Fe) in contact with the underlying substrate. Raman spectrum for the formation of passive metal oxide layer induced by SEPI-10 coating also confirmed that the appearance of characteristic peak of Fe2O3 and Fe3O4.

並列關鍵字

Sulfonated group ； Carboxylic acid group ； Poly(amic acid) ； Plyimide ； Ascrobic acid ； Anticorrosion

參考文獻

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