Polytetrafluoroethylene FIFE membranes

All samples were filtered with a 0.45pm polytetrafluoroethylene (FIFE) membrane filter before injection into the column. 

Fluorinated polymers, especially polytetrafluoroethylene (FIFE) and copolymers of tetrafluoroethylene (TFE) with hexafluoropropylene (HEP) and perfluorinated alkyl vinyl ethers (PFAVE) as well as other fluorine-containing polymers are well known as materials with unique inertness. However, fluorinated polymers with functional groups are of much more interest because they combine the merits of pefluorinated materials and functional polymers (the terms functional monomer/ polymer will be used in this chapter to mean monomer/polymer containing functional groups, respectively). Such materials can be used, e.g., as ion exchange membranes for chlorine-alkali and fuel cells, gas separation membranes, solid polymeric superacid catalysts and polymeric reagents for various organic reactions, and chemical sensors. Of course, fully fluorinated materials are exceptionally inert, but at the same time are the most complicated to produce. 

In a solid polymer electrolyte, such as used in the PEFC, ion mobility is a result of an electrolyte solution integrated into an inert polymer matrix. Early electrolyte membranes developed for the United States space program consisted of treated hydrocarbons, which resulted in poor longevity due to the relatively weaker hydrocarbon bonds [3]. Most modem solid electrolytes are perflourinated ionomers with a fixed side chain of sulphonic acid bonded covalently to the inert, but chemically stable, polymer polytetrafluoroethylene (FIFE) stracture. As a result, the membrane consists of two very different sub-stractures 1) a hydrophilic and ionically conductive phase related to the bonded sulphonic acid groups... 

HEM, hollow-fiber membrane FSM, flat-sheet membrane M, molarity T, temperature V, Hquid velocity gi, gas velocity PP, polypropylene PVDF, polyvinyhdene fluoride FIFE, polytetrafluoroethylene PMP, poly(4-methyl-l-pentene). 

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