新穎質子交換膜; Novel Proton Exchange Membrane

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/6001

Title:	新穎質子交換膜;Novel Proton Exchange Membrane
Authors:	吳千舜;Chien-Shun Wu
Contributors:	化學研究所
Keywords:	直接甲醇燃料電池;質子交換膜;甲醇滲透現象;原位聚合;反微胞型態;nano-ionics;Direct methanol fuel cell (DMFC);Proton exchange membrane (PEM);inverse micelle
Date:	2004-06-16
Issue Date:	2009-09-22 10:11:42 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	直接甲醇燃料電池的質子交換膜主要研究焦點集中於限制薄膜在甲醇水溶液下的過度膨潤，降低甲醇滲透現象(Crossover)並同時維持薄膜的高導電度。本研究利用原位(in-situ)聚合的方式，在PVDF/HFP (Poly (vinylidenefluoride-co-hexafluoropropylene)共聚高分子溶液中做磺酸酚醛的聚合反應並製備成質子交換膜。在此，磺酸酚醛會在高分子表面形成一親水性披覆膜而呈現反微胞(inverse micelle)的型態，且鄰近的磺酸根是暴露於PVDF/HFP球體間所形成的質子滲透通道並且是互相排列整齊，這樣所形成的離子導電機制將會不同於先前其他系統所研究。更進一步，對於在高濃度甲醇水溶液中，因為PVDF/HFP高分子本身具有部分的結晶性，所以會抑制薄膜的過度膨潤而且可保持質子滲透通道的尺寸安定性，進而有效降低薄膜的甲醇滲透現象。本研究的最後將薄膜再做進一步的交聯，使薄膜應用於直接甲醇燃料電池時更具有較高的化學及熱穩定性。 Conventional membranes such as Nafion suffer from the swelling and methanol crossover under high methanol concentration fuel stream. More durable proton exchange membrane (PEM) has received increasing interests from academic and industrial research for direct methanol fuel cell (DMFC) application. However, most efforts to reduce crossover effect is achieved by discriminating water and methanol permeation, usually at the cost of the proton conductivity. This dilemma is resolved by taking advantage of the novel conducting mechanism, which occurs in nano-ionics: membranes with and channels decorated with closely spaced sulfonic groups in connected nano-pores. Here proton transfer is established by the directional tunneling through the surface charge field created by finely dispersed nano flow channel. Previous studies have demonstrated that polymerization of phenolic in the PVdF and PVdF-HFP copolymers solution forms a thin crust of hydrophilic shell on the sol surface. Current study expands such design using inverse micelle formation where the sulfonic groups are exposed and extend in the solvent permeation channel (with dimensions less than 20 nm). The closely spaced arrangements establish a novel proton conducting behavior entirely different from those previously observed in other systems. As a result of the nano-flow structure, crossover is effectively reduced. Since the PVdF-HFP substrate is partially crystallized, the film withstands solvent swell and preserved the membrane dimensions even in high methanol concentration. Further cross-linking of the product leads to highly chemical and thermally stable membrane suitable for the application of direct methanol fuel cell (DMFC) .
Appears in Collections:	[Graduate Institute of Chemistry] Electronic Thesis & Dissertation

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