Nafion, Flemion

Perfluorinated PEMs with sulfonic acid (la = Nafion, Flemion lb = Aciplex 2a = DOW, Hyflon-ion 2b = 3M, 2c = Asahi Kasei 3 = Asahi Glass) and b)s[(perfluoroalkyl sulfonyl] (4) groups for proton conduction. 

This process has been used to make functionalized perlluorovinyl ethers [e.g., F2C = CF0CF2CF(CF3)0CF2CF2S02F] which are copolymerized to form fluorinated membrane materials (Nafion, Flemion), which arc important in chloralkali electrolysis. ... 

The synthesis of the monomers as well as the polymerization of PFSA membranes involve dangerous reactions under conditions of high pressure and temperature. Additionally, the synthesis of the comonomer that is commonly referred to as perfluorosulfonylfluoride ethyl propyl vinyl ether (PSEPVE) involves numerous steps with low yields. These factors contribute to the cost of these materials. The synthesis routes described in detail by Doyle and Rajendran are summarized here. The synthesis of the long-chain PFSA monomers used in commercial systems like Nafion, Flemion, and Aciplex proceeds through... 

XR (sulfonate) comonomer structures Nafion, Flemion CF2=CF0CF2CF(CF3)0CF2CF2S02F... 

Despite perfluorinated polymer electrolytes (Nafion, Flemion, Aciplex) having been used extensively in PEMFCs, their poor thermal mechanical stability (low Tg), high methanol permeability, and extremely high production costs have led to limitations of their large-scale application. Therefore, a variety of hydrocarbon polymer electrolytes have been developed during the past decade, with the greatest emphasis placed on the costs, conductivity, and durability of these materials. At the same time, the poor mechanical stability and inadequate durability of the hydrocarbon polymer membranes were identified as the main barriers to their practical application. 

Nafion , Flemion Aciplex Dow CF2CF0CF2CF(CF3)0CF2CF2S03H CF2CF0CF2CF(CF3)0CF2CF2CF2S03H CF2CFOCF2CF2S03H... 

As discussed in the previous sections, the hydrated cation migration under an applied electric field directly results in the deformation of the material. In fact, when ionomer (Nafion, Flemion) is dry, the interaction between the side chain groups and the cations is very strong and the ionic conductivity of the membrane is very small [Takeji et al. (1982)]. Conversely, when the membrane is hydrated, the interaction between the cations and the anions in the side chains is weakened and it results in bet-... 

Nafion Flemion Aciplex — CF2CF2)m — CFCF2 — CF2 = CF —0—CF2 —CF —0 —CF2CF2 — S02F DuPont Asahi Glass Asahi Kasei... 

FIG U RE 2.2 Chemical structures of perfluorinated ionomers with sulfonic acid (la = Nafion, Flemion lb = Aciplex 2a = Dow, Hyflon Ion 2b = 3M 2c = Asahi Kasei 3 = Asahi Glass) and bis[(perfluoro)alkyl sulfonyl] groups (4). (Reprinted with permission from Peckham, T. J., Yang, Y, and Holdcroft, S. et al., Proton Exchange Membrane Fuel Cells Materials, Properties and Performance, Wilkinson, D. P. et al., Eds., Figure 3.16, 138, 2010, CRC Press, Boca Raton. Copyright (2010) CRC Press.)... 

Ion-selective membranes, e.g. Nafion, Flemion, Na-j -alumina. These materials are highly selective, permitting the transport only of either cations or anions and accompanying solvent. 

Perfluorinated ionomer membranes of the Nafion, Flemion, Dow Membrane type. 

Most widely used perfluorinated membranes are Nafion, Flemion, etc. There are some drawbacks related to these membranes. They are mechanically unstable for... 

A number of companies have produced commercial perfluorosulfonic acid membranes, with trade names including Nafion, Flemion, Aciplex, Aquivion, and Fumion [8]. However, since methanol readily transports across these membranes, the efficiency of DMFCs operating with these membranes is rather low, as the methanol reacts at the cathode to produce carbon dioxide and water (reducing the coulombic efficiency of the cell). It is, therefore, important to modify the properties of these membranes to suppress as much as possible the methanol crossover. 

Perfluorinated ionomer membranes have also been developed by Asahi Chemical and the Asahi Glass Company and commercialised as Aciplex S and Flemion, respectively. The general properties of the long side chain perfluorinated ionomer membranes (e.g. Nafion, Flemion, Aciplex) and the short side chain perfluorinated ionomer membranes (e.g. Dow) are shown in Table 1.2. 

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