Polymerization hexafluoropropylene oxide

Before we discuss our efforts to prepare long-chain fluoroethers that have difunctional termination, let us briefly consider some of the fluoroether work in the literature. Although much work has been done with tetrafluoroethylene oxide, it is quite unstable and therefore difficult to handle experimentally. Consequently, efforts have been centered on hexafluoropropylene oxide polymerization. 

Hexafluoropropylene Oxide HFPO is the most important of the perfluoroepoxides and has been synthesized by almost all of the methods noted. Many attempts have been made to polymerize HFPO (6,8). The most successful has been the reaction of HFPO with fluoride ion at low temperature to give a series of oligomeric acid fluorides which have been end capped to yield stable fluids (eq. 11, where X = H,F). 

Peduoropolyethers, which constitute special class of fluoropolymer, are useful as lubricants,1 elastomers,2 and heat-transfer fluids under demanding conditions. Several commerical products are available, which are generally prepared by ring-opening polymerization of hexafluoropropylene oxide or by the random copolymerization oftetrafluoroethylene and hexafluoropropylene with oxygen under ultraviolet irradiation.3 Direct fluorination of hydrocarbon ethers has been reported4 but must be done very slowly under carefully controlled... 

Acrylamide was successfully polymerized in a supercritical inverse emulsion composed of an ethane-propane mixture as the continuous phase, water and acrylamide as the dispersed phase, and a mixed nonionic surfactant system as the emulsifier [86], AIBN [2,2 -azobis(isobutyronitrile)] was the initiator. The polymerization was subsequently repeated in supercritical CO2 [87]. The C02-philic surfactant used to produce the inverse emulsion was an amide, end-capped poly(hexafluoropropylene oxide). The process yielded polymers of average molecular weights from 5 x 10 to 7 x 10. ... 

Copolymers from tetrafluoroethylene and 40% perfluorovinyl methyl ether are also elastomers (glass-transition temperature — 12°C). The copolymerization is carried out in aqueous emulsion with ammonium perfluoro-octanoate as emulsifier. Vulcanization is possible with hexamethylene diamine via the small amount of perfluoro(4-carboxy methyl butyl vinyl ether) also polymerized into the copolymer. This ether is produced from perfluoroglutaryl fluoride and hexafluoropropylene oxide. 

On the other hand, hexafluoropropylene oxide is stable up to 150°C. The polymerization is carried out with inorganic fluoride ions in solvents such as a-methyl-co-methoxy-tetra(oxyethylene) (tetraglyme) ... 

Peifluoropolyethers Similarly to fluorinated olefins, the introduction of fluorine atoms onto the poly(ethylene oxide) (PEO) backbone has been explored through the family of perfluoropolyethers (sometimes coined perfluoroalkylethers or perfluoropolyalkylethers). Functionalized poly(hexafluoropropylene oxides) are representative perfluoropolyethers that actually attracted early attention for their solubility in SC-CO2 (see Figure 13.5). These polymers are produced by anionic ringopening polymerization of HFP oxide and commercialized as industrial lubricants by Dupont under the name of Krytox . 

Hexafluoropropylene does not polymerize into a homopolymer easily therefore, it can be stored as a liquid. Flowever, it forms industrially useful copolymers and terpolymers with other fluorinated monomers. Oxidation of F1FP yields an intermediate for a number of perfluoroalkyl perfluorovinyl ethers.30... 

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