Tetrafluoroethylene-perfluoropropylene copolymer

Radiation-induced grafting29 was used for the preparation of low-cost polyelectrolyte membranes needed for fuel-cells30. Guzman-Garcia and coworkers29 studied the grafting of poly(styrenesulphonic acid)on polystyrene on a copolymer of poly(tetrafluoroethylene) with polystyrene, and with a copolymer of poly(tetrafluoroethylene) with poly(perfluoropropylene). 

A family of copolymers containing TFE and perfluoromethyl vinyl ether modified with PPVE referred to as MFA is produced by Ausimont (24). The relatively small pendant group —0—CF3 seems to have a similar effect on the crystallinity reduction as is exhibited by —CF3 in FEP (perfluoropropylene-tetrafluoroethylene copolymer) however, the higher reactivity of perfiuoromethyl vinyl ether than that of HFP makes the polymerization process more efficient. The performance characteristics are described in References 11 and 25. 

The preparation of a new class of processable heavily fluorinated aciylic resins with veiy low dielectric constants is described. The title compounds 2 and 5 were prepared through the condensation of the respective aicohols 1 and 4 with aciyloyl chloride. Unlike tetrafluoroethylene, monomers 2 and 5 are ea to process into polymers under normal conditions due to their liquid or semisolid nature. Radical polymerization of the title compounds with a trace amount of azobisisobutyronitrile or methyl ethyl ketone peroxide at 85-100 leads to homopolymers 3 and 6 and copolymer 7. All polymers exhibit dielectric constants around 2.10-2.24 over a frequency region of 500 MHz to 18.5 GHz the variation of dielectric constant values over the measured frequency region is within 0.03 for each polymer. These values are very close to the minimum known dielectric constants of 2.0-2.08 for poly(tetrafluoroeth-ylene) and 1.89-1.93 for a terpolymer of 2,2-bis-(trifluoromethyl)-4,5-difluoro-1,3-dioxole 8, perfluoropropylene and tetrafluoroethylene 9. The dielectric constants for poly(tetraf1uoroethylene) measured with the same method are observed to be around 1.96-1.99 in order to validate the accuracy of our measurement. 

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