Hexafluoroacetone, copolymerization

Other interesting perfluoro ether stmctures can be obtained by copolymerization of hexafluoroacetone with ethylene oxide, propylene oxide, and trimethylene oxide with subsequent fluorination to yield the following stmctures (67) ... 

Uses. Vinyhdene fluoride is used for the manufacture of PVDF and for copolymerization with many fluorinated monomers. One commercially significant use is the manufacture of high performance fluoroelastomers that include copolymers of VDF with hexafluoropropylene (HFP) (62) or chlorotrifluoroethylene (CTFE) (63) and terpolymers with HEP and tetrafluoroethylene (TEE) (64) (see Elastomers, synthetic-fluorocarbon elastomers). There is intense commercial interest in thermoplastic copolymers of VDE with HEP (65,66), CTEE (67), or TEE (68). Less common are copolymers with trifluoroethene (69), 3,3,3-trifluoro-2-trifluoromethylpropene (70), or hexafluoroacetone (71). Thermoplastic terpolymers of VDE, HEP, and TEE are also of interest as coatings and film. A thermoplastic elastomer that has an elastomeric VDE copolymer chain as backbone and a grafted PVDE side chain has been developed (72). 

The copolymerization of carbonyl monomes with alkenes has been even less studied than that between different carbonhyl monomers. The radiation-initiated copolymerization of styrene with formaldehyde proceeds by a cationic mechanism with a trend toward ideal behavior, r = 52 and r2 = 0 at —78°C [Castille and Stannett, 1966]. Hexafluoroacetone undergoes radiation-initiated copolymerization with ethylene, propene, and other a-olefins [Watanabe et al., 1979]. Anionic copolymerizations of aldehydes with isocyanates have also been reported [Odian and Hiraoka, 1972]. 

The precursor polymer was prepared by Tabata et al. (43) using the radiation-induced low-temperature copolymerization of ethylene and hexafluoroacetone ... 

Radiation-Induced Copolymerization of Hexafluoroacetone with a-Olefins... 

Radiation induced copolymerization of hexafluoroacetone xcith a-olefins has been done over a broad temperature range. From these experiments, it was confirmed that ethylene can be copolymerized below its critical temperature to give an alternating copolymer. A radical mechanism is involved at relatively high temperatures below —10°C, the mechanism has been confirmed to be ionic and may be cationic. Propylene can be copolymerized in a way similar to that of ethylene however, the rate of copolymerization was much slower. Isobutylene did not copolymerize with hexafluoroacetone at 0°C. A 1 2 adduct compound was obtained as the main product. At low temperatures, copolymerization proceeds to some extent. 

Copolymerization of Ethylene with Hexafluoroacetone. Conversion curves at — 78° C for three different initial monomer compositions are... 

Figure 4. Arrhenius plot of the copolymerization of ethylene-hexafluoroacetone...

A composition curve of the copolymerization is shown in Figure 7. The composition of one component in copolymers is exactly 50 mole % over a wide range of monomer concentration of the component in monomer mixtures. These results strongly indicate that an alternating copolymerization takes place in the ethylene-hexafluoroacetone system. 

Copolymerization of Propylene with Hexafluoroacetone. The conversion curves of the copolymerization are shown in Figure 12 as a function of irradiation time for equimolar monomer mixtures at 0°, —35°, and — 78°C. The copolymerization rate is much slower than that of the copolymerization of ethylene and hexafluoroacetone. We have data at... 

Radiation-induced curing of plastic coatings has been discussed,8 and radiation-induced polymerization in the solid state reported.87 The radiation chemistry of epoxy-containing electron resists88 and polycondensation induced by ionizing radiation in the urea-formaldehyde system88 have been described. Radiation-induced copolymerization of the following pairs of monomers has been achieved ethylene-hexafluoropropylene,80 tetrafluoroethylene-propylene,81 tetrafluoroethylene-hexafluoropropylene,82 hexafluoroacetone-a-olefins,83 MMA-di- and tri-methacrylates,84 styrene-acrylonitrile,85 buta-1,3-diene-acrylonitrile,88 and acenaphthylene-vinylcarbazole.87... 

Low-temperature, liquid-phase, radiation-induced ( Co y-rays) copolymerization of hexafluoroacetone with ethylene yields the alternating copolymer [(CFs)2C 0 CH2 CH2]re propene appears to behave like its lower homologue in this respect, but the reaction proceeds much more slowly isobutene yields a... 

A combination of gas chromatography and either electron-impact or chemical ionization mass spectrometry has been used to analyse the products of thermal degradation of poly(vinyl fluoride) and of a number of other polymers [poly(vinyl chloride), aromatic polyimides, polyurethane]. The degradation of poly(vinyl-idene fluoride) has been related to its crystalline form. It is claimed that dehydrofluorination may take place preferentially in crystalline segments containing trans sequences. Thermo-oxidative breakdown is modified if vinylidene fluoride is copolymerized with tetrafluoroethylene or hexafluoroacetone. Dehydrofluorination occurred in both copolymers, but in the latter it was preceded by cleavage of the H from the CHj group in the alpha position to the ether bond followed by scission of the C-0 bond. ... 

Their cohesive energy is very high, and they are soluble only in highly polar solvents such as hexafluoroisopropanol or hexafluoroacetone sesquihydrate. These two homopolymers are crystalline (if lactide is optically pure) for PG, = 225°C and Tg 35°C their copolymerization in variable proportions allows the control of their degree of crystallinity as well as their hydrophilicity. The principal application of these copolymers (PGL) is in the biomedical field they are used as biodegradable materials, with their biodegradability being mainly controlled by their capability to absorb water. 

To prepare Teflon AF series, reactions of hexafluoroacetone (HFA) and ethylene oxide (EO) give rise to defluorinated 2,2-bis(trifluoromethyl)-4,5-difluoro-l,3-dioxole (BDD) monomer, followed by the copolymerization with tetrafluoroethylene (TFE). The physical properties of these amorphous copolymers are dependent upon the compositions in the copolymers as shown in Table 4.8. Currently, there are two commercial grades of Teflon AF polymers produced by DuPont, AF-2400 and AF-1600, which contain the composition of copolymers for which n = 0.87 and 0.65, respectively, where n is the molar ratio of the BDD monomers. 

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