Fluoropolymer membranes fuel cells

Souzy, R. and Ameduri, B., Functional fluoropolymers for fuel cell membranes. Prog. Polym. Sci., 30, 644, 2005. 

R. Souzy, C. Boyer, G. David, G. Rostov and B. Ameduri, Reeent Advanees in Functional Fluoropolymers for Fuel Cell Membranes , in ECS Transactions. Eds. T. Fuller, H. Gasteiger, S. Cleghom, V. Ramani, T. Zbao,... 

The fuel cells are classified based on the fuel, operating temperature, electrolyte type, physical state of fuel cell components and the fabrication technology. The polymer electrolyte membrane fuel cell (PEMFC) operating on a methanol-water mixture as a fuel is called a Direct Methanol Fuel Cell (DMFC). DMFC uses sulphonated fluoropolymer, such as NAFION 117 as the electrolyte membrane. Nafion membranes require high levels of humidification and can operate comfortably only within a narrow temperature range of 25°C... 

In contrast to past environmental problems associated with fluorocarbon refrigerants, the exceptional properties of fluorine in polymers have great environmental value. Some fluoropolymers are enabling green technologies such as hydrogen fuel cells for automobiles and oxygen-selective membranes for cleaner diesel combustion. 

One of the first fictional fluoropolymers was poly-1,2,2-trifluorostyrene. On one hand, it has much better oxidation and chemical resistance in comparison with common hydrocarbon polymers and, on the other hand, a wide range of functional groups can be attached to the aromatic ring. A sulfonated polymer was successfully used as a membrane for fuel cells by General Electric Co.3... 

As was noted above, functional fluoropolymers produced by copolymerization of fluoroolefins with functional PFAVE have several unique properties, with the main disadvantage of these materials being the extremely high cost of functional monomers and the resulting high cost of the functional polymers produced from them. The fact that they are so expensive limits their wider industrial application in other fields such as catalysis and membrane separation, except for chlorine-alkali electrolysis and fuel cells, where the only suitable materials are fully fluorinated polymers because of the extreme conditions associated with those processes. 

Perpall, M. W., Smith, D. W., Jr., DesMarteau, D. D. and Greager, S. E. 2006. Alternative trifluorovinyl ether derived fluoropolymer membranes and functionalized carbon composite electrodes for fuel cells. Journal of Macromolecular Science Part C Polymer Reviews 46 297-313. 

We will continue platform extensions, taking Nafion fluoropolymer membranes from chloralkali cells and catalysts to advanced fuel cells, and Kapton polyimide film from flat electronic computer circuits to complex flexible circuits in cell... 

PEMFC (proton exchange membrane) uses fluoropolymer or similar type membranes such as SPEEK. Microbial and direct methanol fuel cells fall into this category also. 

Zhang Y, Pang J, Wu Y, Xu H, Chi X, Li W, Yang Y, Yan G (2012) Novel fluoropolymer anion exchange membrane for alkaline direct methanol fuel cells. J Colloid Interface Sd 381 59-66... 

Gubler, L., Slaski, M., Wallasch, F., Wokaun, A., Scherer, G.G. Radiation grafted fuel cell membranes based on co-grafting of a-methylstyrene and methacrylonitrile into a fluoropolymer base film. J. Membr. Sci. 339, 68-77 (2009)... 

Proton Exchange Membrane (PEM), commonly synonymous with DuPont s Nation membrane and used in both PEM fuel cells and DMFCs, requires aqueous conditions for suitable ionic conductivity and therefore needs insulation against freezing, and requires rigorous humidity control. Although other membrane chemistries are available, the sulfonated tetrafluoroethylene-based fluoropolymer-copolymer chemistry used in Naflon and other brand name membranes is still the material of choice. 

Simplicity and promise of low cost - Fuel cells are extremely simple. They are made in layers of repetitive components, and they have no moving parts. Because of this, they have the potential to be mass produced at a cost comparable to that of existing energy conversion technologies or even lower. To date, the fuel cells are still expensive for either automotive or stationary power generation, primarily because of use of expensive materials, such as sulfonated fluoropolymers used as proton exchanged membrane, and noble metals, such as platinum or ruthenium, used as catalysts. 

The heart of the PEM fuel cell is the proton exchange membrane, which transports protons from the anode to the cathode. The membrane also serves to separate the fuel and oxidant gas phases and electronically insulates the cathode from the anode. The most typical membrane is a sulfonated per-fluorinated polymer. The Nation family of membranes made by DuPont is representative of this class, and is based on a sulfonated tetrafluoroethylene-based fluoropolymer-copolymer, with the chemical structure represented in Figure 1.2. The sulfonic acid (SO3H) groups on the side chains allow the protons or other cations to "hop" from one acid site to another, in the presence of water. The exact mechanism of the proton movement is an area of significant research. An active area of research is the development of hydrocarbon-based... 

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