| 词条 | Perfluoroether |
| 释义 |
Perfluoroethers are a class of organofluorine compound containing one or more ether functional group. In general these compounds are structural analogous to related hydrocarbon ethers, but they exhibit also the distinctive properties of fluorocarbons. The introduction of an ether function to a perfluoro-polymer chain also provides thermoplastic properties to the polymer and makes possible its thermal forming. It is a great technological advantage for producing a large variety of shapes (e.g., beakers, funnels, flasks for laboratory uses, etc...) and to extrude highly chemically resistant tubings. It also confers to the polymer a translucent appearance.[1] Low molecular weight fluorinated ethersAcyclic perfluoroethers are known, e.g. O(C2F5)2, the analogue of diethylether. More interesting and more useful are the cyclic ethers, especially, the epoxides. Thus tetrafluoroethyene oxide and hexafluoropropylene oxide are two of the simplest cyclic perfluoroethers. It is a precursor to perfluoro(methyl vinyl ether) (CF2=CFOCF3) and perfluoro(propyl vinyl ether) are used as a comonomers with tetrafluoroethylene. Polymeric perfluoroethersPerfluoroalkoxy alkanes (PFAs) are fluoropolymers with properties similar to polytetrafluoroethylene (PTFE). Methylfluoroalkoxy (MFA) is a polytetrafluoroethylene perfluoro methylvinylether prepared with a different ratio of PTFE and MVE monomers than for PFA. In these materials, the ether groups are pendant from the polymer backbone. Krytox is a grease generated by the polymerization of hexafluoropropylene oxide. Their chemical formula is F−(CF(CF3)−CF2−O)n−CF2CF3. The ether groups are integral to the polymer chain.[2]Nafion is a perfluorinated polyether with pendant sulfonic acid groups (RSO3H). PrecautionsAt high temperatures or in a fire, perfluoroethers decompose and may release hydrogen fluoride. Any residue must be handled using protective equipment. References1. ^{{cite encyclopedia|authors=Günter Siegemund, Werner Schwertfeger, Andrew Feiring, Bruce Smart, Fred Behr, Herward Vogel, Blaine McKusick|title=Fluorine Compounds, Organic|encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry|publisher=Wiley-VCH|place=Weinheim|year=2002|doi=10.1002/14356007.a11_349}} 2. ^{{cite encyclopedia|title=Fluoroethers and Fluoroamines|authors=Michael G. Costello, Richard M. Flynn, John G. Owens|year=2001|publisher=Wiley-VCH|place=Weinstein|encyclopedia=Kirk-Othmer Encyclopedia of Chemical Technology|doi=10.1002/0471238961.0612211506122514.a01.pub2}} External links
3 : Fluoropolymers|Thermoplastics|Organofluorides |
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