Degradation of perfluorinated

Liu H, Gasteiger HA, LaConti AB, Zhang J (2006) Factors impacting chemical degradation of perfluorinated sulfonic acid ionomers. ECS Trans 1 283-293... 

Inaba M (2009) Chemical degradation of perfluorinated sulfonic acid membranes. In Buechi EN, Inaba M, Schmidt TJ (eds) Polymer electrolyte fuel cell durability. Springer, New York... 

Delaney, W. E. and Liu, W. 2007. Use of FTIR to analyze ex-situ and in-situ degradation of perfluorinated fuel cell ionomers. ECS Transactions 11 1093-1104. 

Xie, T. and Hayden, C. A. 2007. A kinetic model for the chemical degradation of perfluorinated sulfonic acid ionomers Weak end groups versus side chain cleavage. Polymer 48 5497-5506. 

Qiao, J.L., Saito, M., Hayamizu, K., Okada, T. (2006) Degradation of perfluorinated ionomer membranes for PEM fuel cells during processing with H O. J. Electrochem. Soc. 153, A967-A974. 

Chemical Degradation of Perfluorinated Sulfonic Acid Membranes... 

Yonng, C.J., and D.J. Donaldson (2007), Overtone-induced degradation of perfluorinated alcohols in the atmosphere, J. Phys. Chem. A, 111, 13466-13471. 

Ellis DA, JW Martin, AO De Silva, SA Mabury, MD Hurley, MPS Andersen, TJ Wallington (2004) Degradation of fluorotelomer alcohols a likely atmospheric source of perfluorinated carboxylic acids. Environ Sci Technol 38 3316-3321. 

In order to minimize the degradation of macromolecules, the choice of solvent is not a trivial matter. Hydrogen-containing solvents are obviously not suitable, but even halogenated ones such as CFC13 or CC12FCF2C1, usually stable to fluorine, can react violently with this element when irradiated at temperatures near 0°C. We chose two perfluorinated solvents that have been proven safe and suitable for radical fluorination perfluoro-2-(butyl)-tetrahydro-duran (FC-75 Fluorinert from 3M) and hexafluoropropylene oxide (HFPO) oligomers known as Krytox +... 

The products of perfluorination are both white, very different from the original black hydrocarbon polymers. Both materials are moisture-sensitive powders and slowly degraded by atmospheric moisture, 6 more quickly than 5. The materials oxidize iodide ion to iodine owing to the presence of the N—F moiety. A series of iodometric titrations showed that 6 required twice the number of equivalents of titrant as did 5. This result supports the proposed structures 6 having twice as many N—F moieties as 5. 

Xie, T., Hayden, C., Olson, K. and Healy, J. 2005. Chemical degradation mechanism of perfluorinated sulfonic acid ionomer. In Advances in materials for proton exchange membrane fuel cell systems, Pacific Grove, CA, Feb. 20-23, abstract 24. 

The sulfonic acid resins such as Dowex-50 and Amberlyst-15 have been used to promote the alkylation of the more active aromatic rings but attempts to increase their acidity generally resulted in the degradation of the solid. 2 The more strongly acidic perfluorinated resin sulfonic acid, Nafion-H,2>3 has, however, been used to promote the alkylation of benzene and other aromatic compounds. Nafion-H catalyzed the vapor phase reaction between toluene and methanol. When nm at 185°C a 12% yield of the isomeric xylenes was obtained with the ortho isomer the major product. 0 Methylation of phenol at 205°C over this catalyst gave, at 63% conversion. 37% anisole and 10% of a mixture of the ortho and para cresols in a 2 1 ratio. Reaction of anisole with methanol under these conditions resulted in a 14% selectivity to the methyl anisoles at 40% conversion, with the ortho and para isomers formed in nearly equal amounts. ... 

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