Vinyl fluoride, polymerization

The surfactants usually used in the emulsion polymerizations of nonfluorine-containing monomers appear to be unsatisfactory in the case of vinyl fluoride polymerizations [6]. Salts of the higher perfluorinated carboxylic acids are more suitable emulsifiers. Cationic surfactants based on perfluoroalkylpropylamines are used in a recent patent for the emulsion polymerization of vinyl fluoride [36]. 

DuPont is the only known manufacturer of this polymer, which they call Tedlar . The structure is a head-to-tail configuration of the CF monomer there are no fluorines on adjacent carbons. But in reality vinyl fluoride polymerizes in both head-to-head... 

VinyUdene fluoride can be polymerized in saturated fluorinated or fluorochlorinated solvents. These solvents dissolve fluoroalkenes like vinylidene fluoride and organic peroxide catalysts. Polymerization thus takes place in a homogeneous phase and the resulting poly-vinylidene fluoride is insoluble in the solvent, making the product readily separable from the solvent. In addition to organic peroxides, the reaction can be initiated or induced by radiation. This is helpful in avoiding contamination of the product with other reaction components such as the initiator, surfactant, and the others. Alkyl boron activated by oxygen has also been reported to catalyze vinylidene fluoride and vinyl fluoride polymerization in water and solvents. ... 

Vinyl fluoride polymerizes by a free-radical mechanism in both head-to-head and head-to-tail configurations. Commercial PVF (supplied by DuPont Co.) contains 10-12% of head-to-head and tail-to-tail units, also called inversions, Vinyl fluoride does not polymerize as easily as many other vinyl halidesf " ] due to the high electronegativity of fluorine, which is the most electronegative element. VF requires high pressure polymerization, similar to that required for polyethylene, due to its low boiling point (-72°C) and high critical temperature (54.7°C). 

The earliest reported polymerization of vinyl fluoride involved heating a saturated solution of VF in toluene at 67°C at 600 MPa for a period of 16 hours. In another study, benzoyl peroxide was the polymerization initiator. A polymer was produced with a density of 1.39 g/cm which could be dissolved in hot dimethylformamide, chlorobenzene, and other polar solvents. A great many initiators and vinyl fluoride polymerization conditions have been studied. Examples ofbulk f ] and solution[ ][ F[i04] pp lymerizations have been reported. Aqueous suspension or emulsion techniques have been generally preferable over other methods.Vinyl fluoride volatility required the use of moderately high pressures during the polymerization. Photopolymerization of VF, aided by a free-radical initiator, has also been accom-... 

Reaction conditions must be controlled since HF is also an excellent polymerization catalyst. Controlled reaction conditions can alternatively lead to vinyl fluoride or to HFC-152a (CH2CHF2). The latter can be thermally cracked to form vinyl fluoride. 

Copolymers of VF and a wide variety of other monomers have been prepared (6,41—48). The high energy of the propagating vinyl fluoride radical strongly influences the course of these polymerizations. VF incorporates well with other monomers that do not produce stable free radicals, such as ethylene and vinyl acetate, but is sparingly incorporated with more stable radicals such as acrylonitrile [107-13-1] and vinyl chloride. An Alfrey-Price value of 0.010 0.005 and an e value of 0.8 0.2 have been determined (49). The low value of is consistent with titde resonance stability and the e value is suggestive of an electron-rich monomer. 

The resulting complexes can be effectively employed as single component catalysts to homopolymerize ethylene or copolymerize ethylene with acrylates [50, 51] and a variety of other polar monomers including vinyl ethers, [51,52] vinyl fluoride [53], iV-vinyl-2-pyrrolidinone, and AMsopropylacrylamide [54], In fact, the resulting catalysts are so robust that they can be used as single component catalysts in aqueous emulsion homo-polymerization of ethylene and copolymerization of ethylene with norbomenes and acylates [55]. 

Although vinyl fluoride was prepared around 1900, it was believed to be resistant to typical vinyl polymerization. German scientists prepared vinyl fluoride through reaction of acetylene with hydrogen fluoride in the presence of catalysts in 1933. 

It was not until 1958 that DuPont scientists announced the polymerization of vinyl fluoride forming poly(vinyl fluoride)—PVF (Equation 6.52). Polymerization is accomplished using peroxide catalysts in water solutions under high pressure. 

The effect of pressure on polymerization, although not extensively studied, is important from the practical viewpoint since several monomers are polymerized at pressures above atmospheric. Pressure affects polymerization through changes in concentrations, rate constants, and equilibrium constants [Ogo, 1984 Weale, 1974 Zutty and Burkhart, 1962], The commercial polymerizations of most gaseous monomers (e.g., vinyl chloride, vinylidene chloride, tetrafluoroethylene, vinyl fluoride) are carried out at very moderate pressures of about 5-10 MPa (1 MPa = 145 psi), where the primary effect is one of increased... 

Unsaturated vinyl esters for use in polymerization reactions are made by the esterification of olefins. The most important ones are vinyl esters vinyl acetate, vinyl chloride, acrylonitrile, and vinyl fluoride. The addition reaction may be carried out in either the liquid, vapor, or mixed phases, depending on the properties of the acid. Care must be taken to reduce the polymerization of the vinyl ester produced. 

Vinyl fluoride is polymerized by free radical processes as most common commercial fluororopolymers, but it is more difficult to polymerize than TFE or VDF and requires higher pressures.62 The temperature range for the polymerization in aqueous media is... 

Polymerization of Styrene Solutions of Volatile Hydrocarbons. Addition of Hydrocarbon before Polymerization. Bulk Polymerization. Expandable polystyrene was prepared inadvertently in 1945 in an attempt to bulk copolymerize 10% isobutylene with styrene. The product formed a low density foam when heated (96). An early method (1950) for rendering polystyrene expandable by petroleum ether was to dissolve 6 parts of petroleum ether in a 40% solution of polystyrene in benzoyl peroxide-catalyzed styrene and to hold the mass for 28 days at 32 °C. (124). In a recent version of this process, the monomer (chlorostyrene) and blowing agent (trichlorofluoromethane) in a poly (vinyl fluoride) bag were irradiated with y-rays (105). 

The major commercial fluoropolymers are made by homopolymerization of tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE),vinyhdene fluoride (VF2), and vinyl fluoride (VF), or by co-polymerization of these monomers with hexafluoropropylene (HFP), perfluoro(propyl vinyl ether) (PPVE), per-fluoro(methyl vinyl ether) (PMVE), or ethylene. The polymers are formed by free-radical polymerization in water or fluorinated solvents. 

The facts found with pulsed radio frequency discharge that (1) the largest increase in dangling bonds is observed with ethylene and fluorohydrocarbons (e.g., vinyl fluoride and vinylidene fluoride), (2) the dangling bonds in tetrafluoro-ethylene decrease, and (3) dangling bonds in most perfluorocarbons decrease support a significant difference between the plasma polymerization of hydrocarbons and that of perfluorocarbons summarized above. 

Vinyl fluoride (VF) [75-02-5] (fluoroethene) is a colorless gas at ambient conditions. Vinyl fluoride is flammable in air between the limits of 2.6 and 22 vol.%. Minimum ignition temperature for VF and air mixtures is 400°C. Adding a trace amount (<0.2%) of terpenes is effective to prevent spontaneous polymerization of vinyl fluoride. Inhibited vinyl fluoride has been classified as a flammable gas by the U.S. Department of Transportation. 

Vinyl fluoride imdergoes free-radical polymerization.The first polymerization involved heating a saturated solution of VF in toluene at 67° C under 600 MPa for 16 hr. A wide variety of initiators and polymerization conditions have been explored. Examples of bulk and solution polymerizations exist however, aqueous suspension or emulsion method is generally preferred. Copolymers of VF and a wide variety of other monomers have been prepared. More recently, interpolymers of VF have been reported with tetrafluoroethylene and other highly fluorinated monomers, such as hexafluoropropylene, perfluorobuty-lethylene, and perfluoroethylvinylether. 

Tapes. A great variety of tapes find application in electrical equipment. Some tapes contain filler materials in macroscopic form such as glass fibers, mica flakes, and cloth others have finely divided filler particles or no fillers at all. In the heavily filled materials the polymeric binders are present in small fractions, and the major emphasis may be on their adhesive capabilities rather than on their properties as dielectric materials. Most of the polymers used in tapes have already been mentioned in connection with other insulation applications, for example, polyesters, aromatic polyamides, polyimides, and polypropylene. Other polymers frequently used for electrical tapes are vinyls, including poly(vinyl fluoride) these are particularly well suited as conformable tapes. Polytetrafluoroethylene (Teflon TFE) has also been fabricated into tape constructions, frequently in combination with adhesives to provide a bondable material. 

VINYL FLUORIDE or VINYL FLUORIDE MONOMER (75-02-S) Flammable gas. Able to polymerize unless inhibited (0.2% terpenes are recommended). Violent reaction with oxidizers. Heat of combustion forms toxic hydrogen fluoride gas. May accumulate static electrical charges, and may cause ignition of its vapors. 

Bulk Polymerization of Vinyl Fluoride Benzoyl Peroxide Initiated. 338... 

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