無機/高分子混成材料質子交換膜

Abstract

本研究中嘗試合成新的無機/有機混成高分子材料應用於燃料電池的質子交換膜，同時對此類新材料進行研究與分析，希望能藉此開發出另一種較低成本的燃料電池質子交換膜，來針對目前昂貴的商業化薄膜Nafion進行部份取代。本研究中主要分為兩部份，第一部份為合成側鏈上帶有磺酸根的無機/有機混成高分子，磺酸根的引入方式為利用帶有氨基的矽烷氧化物和1,3 propane sultone進行反應，再將矽烷氧化物上的烷氧官能基(-OR)進行水解-縮合反應，合成有機/無機混成高分子。為了加強薄膜的機械性質，也經由部份具有氨基的矽烷氧化物和環氧樹脂反應，引入具苯環類的環氧樹脂來加強薄膜的機械性質。第二部份則為合成具有鹼性官能基的無機/有機混成高分子，再混摻小分子的酸到高分子中，合成所謂的acid-base complex質子交換膜，其合成方法與第一部份類似，但不做磺酸化的反應，直接讓薄膜上的胺基和小分子的酸形成酸鹼複合的結構。 在薄膜的性質分析上，利用FTIR來鑑定薄膜的結構，以TGA、DSC、SEM進行熱性質的鑑定與微觀型態的分析，以交流阻抗和擴散槽實驗分析其質子導電度與甲醇穿透率，以抗張強度的測試來做機械性質的分析。在第一部份的研究中，所得到的質子導電度為10-4~10-3 S/cm，而第二部份的研究中所得到的質子導電度約為10-3~10-2 S/cm，接近Nafion 117的質子導電度。而在甲醇穿透率的探討中，我們所合成的薄膜的甲醇穿透率約為10-7~10-6 cm2/s，較Nafion 117的甲醇穿透率(10-6 cm2/s)有所改善。藉由本項研究的進行，提供了另一種可應用於燃料電池質子交換膜的材料的探討。

In our study, we try to synthesize a series of novel inorganic-organic hybrid polymer to be used in proton exchange membrane of fuel cell. We hope to exploit a lower cost membrane to partially replace nafion, which is an expensive commercial proton exchange membrane in fuel cell. There are two major parts in our research. First, we synthesize a series of novel hybrid polymer which contains sulfonic acid functional group in side chain. To introduce sulfonic acid into our polymer, two kinds of silane, 3-aminopropylmethyldiethoxysilane(APDES) and 3-aminopropyl-triethoxysilane(APTES), which contains amine functional group, are used to react with 1,3 propane sultone. After successfully introduce sulfonic acid group, we do a sol gel process via hydrolysis and condensation of alkoxide functional group (OR) of silane. Besides, we introduce DGEBA via a ring-opening reaction with APDES to improve the mechanical property of membrane. In second part of our study, we synthesize a new serial of hybrid basic polymer and doping some inorganic acid into our polymer to get an acid-base complex structure proton exchange membrane. The reaction of second part of our study is similar with first one part. The major difference is not to do sulfonation reaction in inorganic-organic hybrid polymer, but to dope inorganic acid into polymer directly via acid-base complex formation. In analysis part, we use FTIR to determine structure of membrane. Furthermore, TGA, DSC and SEM are used in thermal properties and morphology analysis. AC impedance analysis and diffusion cell are used in proton conductivity and methanol permeability analysis. Tensile strength testing is used in mechanical property analysis. In the first part of our study, the proton conductivity of membrane is in the range of 10-4~10-3 S/cm. In second part of our study, the proton conductivity is in the range of 10-3~10-2 S/cm, which close to proton conductivity of nafion in our testing system. The methanol permeability of our study is in the range of 10-7~10-6 cm2/s, which is better than permeability of nafion 117(10-6 cm2/s). By our study, we provide an alternative proton exchange membrane research for fuel cell application.