Fluorine-containing polymers poly

Fluorine-containing Polymers 13.6 POLY(VINYL FLUORIDE) (PVF)... 

The processability of fluorine-containing polymers is improved by replacement of one or more of the fluorine atoms. Replacing one of the eight fluorine atoms with a trifluoromethyl group gives a product called FEP or Viton, actually a copolymer of tetrafluoroethylene and hexafluoropropylene (Equation 6.53). Polytrifluoromonochloroethylene (PCTFE, Kel F) (Equation 6.54), in which one fluorine atom has been replaced by a chlorine atom, has a less regular structure and is thus more easily processed. Poly(vinylidene fluoride) (PVDF, Kynar) (Equation 6.55) is also more easily processable but less resistant to solvents and corrosives. 

The scheme developed for calculation of the glass transition temperatures (Tg) of fluorine-containing polymers gives a value for poly(octafluorostyrene) which is in... 

The volume of commercial fluorine containing polymers is not large when compared with other polymers, such as poly(vinyl chloride). Fluoropolymers, however, are required in many important applications. The main monomers are tetrafluoroethylene, trifluorochloroethylene, vinyl fluoride, vinylidine fluoride, and hexafluoropropylene. 

Also, low molecular weight fluorine-containing polymers form from peifluoroaromatic compounds through a loss of aromaticity when they react with bis(fluoroxy)difluoromethane. More interesting is the formation of poly(a,a,a, a -tetrafluoro-/7-xylylene) by a polymerization technique that closely resembles the preparation of poly(p-xylylene) by vacuum pyrolysis of a dimer ... 

Akutin and co-workers [159] made block and graft copolymer of fluorine-containing polymers or polysiloxanes as one component and poly(methyl methacrylate), poly(vinyl chloride), and ethylcellulose as the second. During the irradiation, samples were withdrawn at regular intervals in order to determine the extent of reaction by the decrease in solution viscosity, rj. In other cases, a recombination of macroradicals into new polymeric species caused an increase in the viscosity. The sign and rate of change of rj was thus different for different systems. 

While carbon and proton NMR studies are most commonly reported, several of the other nuclei listed in Table 3.1 (fluorine, phosphorus, nitrogen, and silicon) have made important contributions to materials characterisation. Fluorine NMR ranks only below proton NMR in sensitivity and provides a valuable probe of fluorine-containing polymers, such as poly(viny fluoride) [10]. The fluorine chemical shifts are much more sensitive to structural defects than protons, as shown in Figure 3.11, which compares the F spectra for... 

Mu JX, Zhang CL, Chen J, Jiang ZH, Kireev W (2006) Synthesis of functionalized fluorine-containing hyperbranched poly(aryl ether ketones) Jot optical applications. Polym Sci Ser A 48 1035-1040... 

In 1954 the surface fluorination of polyethylene sheets by using a soHd CO2 cooled heat sink was patented (44). Later patents covered the fluorination of PVC (45) and polyethylene bottles (46). Studies of surface fluorination of polymer films have been reported (47). The fluorination of polyethylene powder was described (48) as a fiery intense reaction, which was finally controlled by dilution with an inert gas at reduced pressures. Direct fluorination of polymers was achieved in 1970 (8,49). More recently, surface fluorinations of poly(vinyl fluoride), polycarbonates, polystyrene, and poly(methyl methacrylate), and the surface fluorination of containers have been described (50,51). Partially fluorinated poly(ethylene terephthalate) and polyamides such as nylon have excellent soil release properties as well as high wettabiUty (52,53). The most advanced direct fluorination technology in the area of single-compound synthesis and synthesis of high performance fluids is currently practiced by 3M Co. of St. Paul, Minnesota, and by Exfluor Research Corp. of Austin, Texas. 

The inability to process PTFE by conventional thermoplastics techniques has nevertheless led to an extensive search for a melt-processable polymer but with similar chemical, electrical, non-stick and low-friction properties. This has resulted in several useful materials being marketed, including tetrafluoro-ethylene-hexafluoropropylene copolymer, poly(vinylidene fluoride) (Figure 13.1(d)), and, most promisingly, the copolymer of tetrafluoroethylene and perfluoropropyl vinyl ether. Other fluorine-containing plastics include poly(vinyl fluoride) and polymers and copolymers based on CTFE. 

As part of an effort to develop high-performance, high-temperature-resistant polymers for microelectronics applications, we also recently described a series of both partially fluorinated and nonfluorinated poly(aryl ether ketone)s containing amide, amide-imide, cyano oxadizole, or pyridazine groups and characterized their thermal and electrical properties.11... 

A fluorine-containing poly(carbonate) was first synthesized by Knunyants and co-workers from Bisphenol AF and phosgene.2 However, detailed properties of this polymer other than the softening temperature of 170°C have not been reported. 

The solubility is generally improved by the introduction of fluorine atoms into aromatic condensation polymers. Poly(carbonate)s containing hexafluoroisopropylidene units are much more soluble than Bisphenol A poly(carbonate) (3). All of the hexafluoroisopropylidene-unit-containing poly(carbonate)s become soluble in acetone, ethyl acetate, chloroform, and dimethyl sulfoxide (DMSO) in addition to the solvents of Bisphenol A poly(carbonate) (3). Colorless, transparent, and flexible films are prepared from hexafluoroisopropylidene-unit-containing poly(carbonate)s by casting or pressing. 

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