摘 要
本研究旨在探討含三氟甲基族之磺酸化聚醚碸(sulfonated polyethersulfone; SPES)經聚乙二醇(polyethylene glycol, PEG)改質後摻雜有機改質蒙脫土(organo-modified montmorillonites, O-MMT)複合材料質子交換膜的製備方法、性質分析及其對於甲醇滲透率之影響。由於甲醇燃料會經由薄膜滲透到電極，造成陰極阻抗增加，導致電池性能及壽命降低，故本研究在薄膜中摻雜進O-MMT，藉由O-MMT的層狀結構彎曲甲醇滲透的途徑，以降低甲醇滲透率。當單體以經由控制6氟-雙酚A (hexafluoro bisphenol A, 6F-BPA)、4-氟苯碸(4-fluorophenyl sulfone, 4-FPS)、氫醌2-鉀磺酸鹽(hydroquinone 2-potassium sulfonate, HPS)、聚乙二醇之莫耳比組合進行聚縮合反應，成功合成改質磺化聚合物，再加入不同含量比例之有機改質蒙脫土，製備成改質含氟磺化聚醚碸/O-MMT複合材料薄膜，且以FT-IR、1H NMR等分析證實所得複合膜為預期之改質含氟磺化聚醚碸/O-MMT複合材料。經由吸水率、接觸角、甲醇滲透率測試後發現，改質膜加入黏土後，由於黏土之層狀分散結構會扭曲甲醇滲透之孔道，使得甲醇滲透率從1.3 ×10-5下降至6.8 ×10-6 cm2/s，但影響質子傳導率之薄膜含水率也從23.8 wt%，小幅下降到20.0 wt%，此因在添加改質劑聚乙二醇之親水特性影響下，使下降幅度較低，故為使聚合物薄膜有較佳的選擇性比(質子傳導度對甲醇滲透率比)，必須同時考量親水改質劑及黏土的添加量，進而使單電池性能得到改善。
關鍵詞：含氟磺酸化聚醚碸、奈米黏土、複合材料
Abstract
In this study, PEG-modified sulfonated polyfluoroethersulfone/O-MMT composites and their proton exchange membranes were prepared and characterized. In the experiment, after organo-modified montmorillonites (O-MMT) were added to proton exchange membranes, it was found that the presence of O-MMT impermeable sheets leads to tortuous diffusion pathways against methanol across the membrane, and consequently decreases the methanol permeation rate. Under the conditions of 4-FPS/HPS/6F-BPA/PEG at a feeding molar ratio of 100/60/35/5, reaction temperature of 160℃ and 24 hrs reaction, 60% of the theoretical degree of modified sulfonation copolymers were obtained. Following this, varying contents of O-MMT, the PEG-modified sulfonated polyfluoroethersulfone/O-MMT composite membranes, were fabricated. The characteristic of composite membranes were confirmed using FT-IR, 1H NMR. After completing water uptake tests, contact angle analysis, and a methanol permeability test, we found that the thin sheet structure of O-MMT bends the path of methanol, and the methanol permeability decreased. In order to improve the selectivity of the composite membranes, we need to consider both the content of hydrophilic modifier and the O-MMT of the composite membranes.
Keywords: Fuel Cell, Proton Exchange Membrane, Polyethersulfone, O-MMT