Perfluoro?methyl vinyl ether

FLUORINECOMPOUNDS, ORGANIC - FLUOROETHERS AND FLUORO AMINES] (Volll) Perfluoro (methyl vinyl ether) [1187-93-5]... 

FLUORINECOPPPOUNDS,ORGANIC - FLUORINAPED ALIPPiATIC COPPPOUNDS] (Vol 11) Poly(tetrafluoroethylene-co-perfluoro(methyl vinyl ether)... 

In the 1960s and 1970s, additional elastomers were developed by Du Pont under the Viton and Kalrez trademarks for improved low temperature and chemical resistance properties using perfluoro(methyl vinyl ether), CF2=CFOCF3, as a comonomer with vinyUdene fluoride and/or tetrafluoroethylene (12,13) (see Fluorine compounds, organic-tethafluoroethylene polypous and copolyp rs). 

Fig. 3. The percent volume swell in benzene after seven days at 21°C compared with the wt % of fluorine on standard recommended compounds. A, copolymers of vinyUdene fluoride—hexafluoropropylene B, terpolymers of vinyUdene fluoride—hexafluoropropylene—tetrafluoroethylene C, terpolymers of vinyhdene fluoride—hexafluoropropylene—tetrafluoroethylene-cure site monomer D, copolymer of tetrafluoroethylene—perfluoro(methyl vinyl ether)-cure...

Tetrafluoroethylene-peifluoro(methyl vinyl Kalrez Du Pont -40% perfluoro(methyl vinyl ether) Ex. air oxidation... 

In attempts to further improve the stability of fluorine-containing elastomers Du Pont developed a polymer with no C—H groups. This material is a terpolymer of tetrafluoroethylene, perfluoro(methyl vinyl ether) and, in small amounts, a cure site monomer of undisclosed composition. Marketed as Kalrez in 1975 the polymer withstands air oxidation up to 290-315°C and has an extremely low volume swell in a wide range of solvents, properties unmatched by any other commercial fluoroelastomer. This rubber is, however, very expensive, about 20 times the cost of the FKM rubbers and quoted at 1500/kg in 1990, and production is only of the order of 1 t.p.a. In 1992 Du Pont offered a material costing about 75% as much as Kalrez and marketed as Zalak. Structurally, it differs mainly from Kalrez in the choice of cure-site monomer. 

Many other crosslinking reactions are used in commercial applications. A variety of halogen-containing elastomers are crosslinked by heating with a basic oxide (e.g., MgO or ZnO) and a primary diamine [Labana, 1986 Schmiegel, 1979]. This includes poly(epichlorohydrin) (Sec. 7-2b-6) various co- and terpolymers of fluorinated monomers such as vinylidene fluoride, hexafluoropropene, perfluoro(methyl vinyl ether), and tetrafluoroethylene (Sec. 6-8e) and terpolymers of alkyl acrylate, acrylonitrile, and 2-chloroethyl vinyl ether (Sec. 6-8e). 

Poly[tetrafluoroethene-co-trifluoro(trifluoromethoxy)ethene] also decomposes at lower temperatures than perfluorinated macromolecules, and the major products of pyrolysis include hydrogen fluoride [65], tetrafluoroethene, hexafluoroethane and perfluoro(methyl vinyl) ether [64]. 

In general the nitroso rubbers also suffer from a poor resistance to ionising radiation, sensitivity to degradation by organic bases, highly toxic degradation products and an exceptionally high cost. The advent of the rubbers based on perfluoro(methyl vinyl ether) considered above and of the phosphonitrilic elastomers considered below would appear to put the commercial future of these materials in extreme doubt. 

Perfluoro (Methyl Vinyl Ether), and Certain Cure Site Monomers... 

A new high-performance elastomer, prepared from tetrafluoroethylene (TFE) and perfluoro(methyl vinyl ether) (PMVE), and characterized by outstanding resistance to chemical attack and excellent thermal stability, was reported recently by Barney et al. (I) of our laboratory. That paper described a rubbery perfluorinated dipolymer that could not be crosslinked using ordinary techniques because of its chemical inertness, and also a terpolymer in which an unspecified third monomer was used to introduce active crosslinking sites. 

Polymerization. Copolymers of tetrafluoroethylene/perfluoro(methyl vinyl ether) and the nitrile (1-4 mole ) have been prepared batch-wise in a stirred autoclave using an aqueous ammonium persulfate or ammonium persulfate-sodium sulfite redox couple system at 40°-100° C. The TFE/PMVE gas mixture was pressured, as required, to maintain the pressure and the nitrile pumped in solution in trichlorotrifluoro-ethane. After completion of the reaction, polymer was isolated from the latex (25-30 solids) by coagulation using ethanol and aqueous magnesium chloride solution. It was washed with alcohol/water solutions and dried at 70 °C in an oven under nitrogen. Mass balance indicated that most of the nitrile had been incorporated. 

The polymerization work reported herein requires compression of tetrafluoroethylene-perfluoro(methyl vinyl ether)mixtures. This operation must be considered potentially hazardous and should be carried out only in adequately barricaded areas. 

Polymer (B) Characterization poly[tetrafluoroethylene-co- perfluoro(methyl vinyl ether)] 2006BEL 49.3 mol% perfluoro(methyl vinyl ether), TgfK = 265.2, p = 2.02 g/cm DuPont Performance Elastomers, L.L.C., Wilmington, DE ... 

Mw/g.mol" = 100000, 15-55 mol% perfluoro(methyl vinyl ether), Tg/K = 271, Dyneon Perfluoroelastomer PFE, D5meon GmbH Co. KG, Burgkirchen, Germany... 

Difluoroketene is also generated in the gas phase by electron impact mass spectrometry of perfluoro methyl vinyl ether and neutralization-reionization of the resulting ion (Scheme 7.40). Electropositive substituents have the opposite effect and stabilize ketenes, as found computationally and experimentally and as exemplified by silyl-substituted ketenes. 

Irradiation of the copolymers of PTFE at ambient temperature will generally lead to degradation of the polymer. Both FEP and poly(tetrafluoroethylene-co-perfluoro-propylvinylether) PFA undergo predominantly chain scission which is also accompanied with a reduction of the mechanical properties [113]. However, with PFA, when the percentage of the comonomer is at a relatively high level, ca. 30% of perfluoro (methyl vinyl ether), there is some evidence of crosslinking [102]. The crosslinking may be due to the more rubbery nature of this copolymer at ambient temperature. 

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