The Free-Radical Chemistry of Fluoroketones. II. Reaction with Unsaturated Compounds

Howard, Edward G.; Sargeant, P. B.

doi:10.1080/10601326708053754

Cited by 12 publications

(2 citation statements)

References 5 publications

(1 reference statement)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, it is likely that this ketone may be either hydrolytically or oxidatively unstable and undergo additional degradation reactions in the presence of water or radical species. 35,36 The fact that the OCV has remained relatively high is not especially surprising since very little conductivity is needed to measure a potential with zero current. Interestingly, the 3M ionomer would be expected to experience the same reaction sequence for the backbone t-fluorine abstraction yet 3M-1 has no discernable HFR increase and 3M-2 has only a slight increase near the end of life (Fig.…”

Section: • • [ ] +  +mentioning

confidence: 99%

Liquid Chromatography/Mass Spectrometry Analysis of Effluent Water from PFSA Membrane Fuel Cells Operated at OCV

Yandrasits¹,

Комлев²,

Kalstabakken³

et al. 2021

J. Electrochem. Soc.

View full text Add to dashboard Cite

Perfluoroalkylsulfonic acid (PFSA) ionomer membranes degrade under accelerated testing conditions such as open circuit voltage (OCV). Fluoride release rate is commonly used for evaluating the membrane degradation rate; however, many proposed degradation mechanisms should result in the release of small molecule polymer fragments. Liquid chromatography/mass spectrometry (LC/MS) methods are well suited to analyze for these fragments and provide insight into the degradation reactions. Accelerated OCV durability tests were conducted on membrane electrode assemblies made with 3M Ionomer ™ or Nafion™ XL membranes. Effluent water was analyzed for fluoride, sulfate, and trifluoroacetic acid by ion chromatography (IC) and other polymer fragments by LC/MS. The detection of partially hydrogenated side chain fragments and long chain dicarboxylic acids suggest hydrogen atoms play a significant role in these reactions. The results of this study show the possibility that more than one reaction may occur at the tertiary fluoride on the polymer backbone. The presence of a tertiary fluoride on the backbone and side chain of the Nafion™ XL membranes allows for these reactions in more than one location on this polymer. Performance loss for the Nafion™ XL samples during these tests is consistent with adsorption of ionomer fragments on the catalyst surface.

show abstract

Section: • • [ ] +  +mentioning

confidence: 99%

Liquid Chromatography/Mass Spectrometry Analysis of Effluent Water from PFSA Membrane Fuel Cells Operated at OCV

Yandrasits¹,

Комлев²,

Kalstabakken³

et al. 2021

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…Based on the previously reported spatial location of this proposed reaction (5), the entire membrane might not need to degrade, just a continuous, thin, region resulting in a layer with little or no conductivity. However, it is possible that this ketone may be either hydrolytically or oxidatively unstable and may undergo additional degradation reactions in the presence of water or radical species (30,31). The fact that the OCV has remained relatively high is not especially surprising since very little conductivity is needed to measure a potential with zero current.…”

Section: Ocv and Ic Resultsmentioning

confidence: 99%

(Invited) Liquid Chromatography/Mass Spectrometry Analysis of Effluent Water from Perfluoroalkylsulfonic Acid (PFSA) Membrane Degradation Studies at Accelerated Durability Test Conditions

Yandrasits¹,

Комлев²,

Kalstabakken

et al. 2020

ECS Trans.

View full text Add to dashboard Cite

Perfluoroalkylsulfonic acid (PFSA) ionomer membranes degrade under accelerated testing conditions such as open circuit voltage (OCV). Analyzing effluent water for fluoride ion release rate is a primary method for evaluating the membrane degradation rate. However, many proposed degradation reaction pathways should result in the release of small molecule polymer fragments. Liquid chromatography/mass spectrometry (LC/MS) methods are well suited to analyze for these fragments and provide insight into the degradation reactions. Accelerated OCV durability tests were conducted on membrane electrode assemblies made with 3M Ionomer or Nafion™ membranes. Effluent water was analyzed for fluoride, sulfate, and trifluoroacetic acid by ion chromatography (IC) and other polymer fragments by LC/MS. The results of this study imply measurable degradation occurs at the tertiary fluoride on the polymer backbone or the ether oxygen connecting the side chain to the backbone. In Nafion™, these structural features also exist in the ionomer sidechain.

show abstract

Glass Transition Temperatures of Polymers

Andrews

Grulke

1999

The Wiley Database of Polymer Properties

View full text Add to dashboard Cite

VI-244 4.6. Poly(benzimidazoles) VI-245 4.7. Poly(benzothiazinophenothiazines) VI-245 4.8. Poly(benzothiazoles) VI-245 4.9. Poly(benzoxazlnes) VI-245 4.10. Poly(benzoxazoles) VI-245 4.11. Poly(carboranes) VI-245 4.12. Poly(dibenzofurans) VI-246 4.13. Poly(dioxoisoindolines) VI-246 4.14. Poly(fluoresceins) VI-247 4.15. Poly(furan tetracarboxylic acid diimides) VI-247 4.16. Poly(oxabicyclononanes) VI-247 4.17. Poly(oxadiazoles) VI-248 4.18. Poly(oxindoles) VI-248 4.19. Poly(oxoisoindolines) VI-248 4.20. Poly(phthalazines) VI-248 4.21. Poly(phthalides) VI-248 4.22. Poly(piperazines) VI-248 4.23. Poly(piperidines) VI-249 4.24. Poly(pyrazinoquinoxalines) VI-249 4.25. Poly(pyrazoles) VI-249 4.26. Poly(pyridazines) VI-249 4.27. Poly(pyridines) VI-249 4.28. Poly(pyromellitimides) VI-249 4.29. Poly(pyrrolidines) VI-250 4.30. Poly(quinones) VI-250 4.31. Poly(quinoxalines) VI-250 4.32. Poly(triazines) VI-252 4.33. Poly(triazoles) VI-252 Table 5. Copolymers VI-252 G. References VI-253 A. INTRODUCTIONAmorphous (noncrystalline) polymeric solids are either glasses or rubbers. A glassy polymer lacks long range order, and is below the temperature at which molecular motions take place on the time scale of the experiment. A rubbery polymer is above the temperature at which molecular motions take place on the time scale of the experiment. The glass transition temperature, T g , is the critical temperature that separates glassy behavior from rubbery behavior. Many amorphous solids, including polymers, organic liquids, biomaterials, some metals and alloys, and inorganic oxide glasses, exhibit glass transition temperatures. The dramatic change in the local movement of polymer chains at T g leads to large changes in a host of physical properties. These properties include density, specific heat, mechanical modulus, mechanical energy absorption, dielectric coefficients, acoustical properties, viscosity, and the rate of gas or liquid diffusion through the polymer, to name a few. Any of these properties can be used, at least in a crude manner, to determine T g . References page VI -253 Specific volume Gl assCrystal l i zati on vol ume change Li qui d

show abstract

The Free-Radical Chemistry of Fluoroketones. II. Reaction with Unsaturated Compounds

Cited by 12 publications

References 5 publications

Liquid Chromatography/Mass Spectrometry Analysis of Effluent Water from PFSA Membrane Fuel Cells Operated at OCV

Liquid Chromatography/Mass Spectrometry Analysis of Effluent Water from PFSA Membrane Fuel Cells Operated at OCV

(Invited) Liquid Chromatography/Mass Spectrometry Analysis of Effluent Water from Perfluoroalkylsulfonic Acid (PFSA) Membrane Degradation Studies at Accelerated Durability Test Conditions

Glass Transition Temperatures of Polymers

Contact Info

Product

Resources

About