Fluorine containing copolymers

II. Elementorganic polymers and copolymers copolymers of fluorinated olefins [10-21] poly(perfluoroalkyl- methacrylates) and perfluoroalkylmethacrylates copolymers [1-3, 22-34] poly(organosiloxanes) [25, 35] fluorine-containing poly(organo siloxanes) [36] fluorine-containing copolymers with side functional (hydroxy) groups [37, 38], and others [1]. 

The New Fluorine Containing Copolymers - Prospective Materials for Covers of Optical Fibres... 

Three polymers, listed in Table 26.6, were selected for further work in which the effect on ITV of fillers, antioxidants and UV absorbers was to be examined. The effect of fillers was explored in the fluorine containing copolymer, the silicone copolymer and polyethylene polyethylene was selected for antioxidant and UV absorber study because of the three it is the most susceptible to oxidation. These results showed that there was a general deterioration compared with pure polymers, although hydrated alumina showed some benefit in polyethylene and silicone rubbers. However such results were not general - alumina hydrate for example deteriorates the performance of fluorine copolymers. The following tables summarize these effects. (Tables 26.6, 26.7, 26.8). 

As mentioned previously, interest in fluorine-containing copolymers has been particularly concerned with the development of rubbers. Many copolymers have been investigated but the bulk of the commercial production of fluoroelastomers is accounted for by vinylidene fluoride copolymers, of which those with hexafluoropropylene are the most important. Vinylidene fluoride-hexafluoropropylene copolymers were first introduced during the mid-1950 s. 

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. 

Other fluorine-containing plastics These materials, in general, attempt to compromise between the exceptional end-use properties of p.t.f.e. and the processability of ordinary thermoplastics. Examples include polychlor-trifluorethylene, tetrafluorethylene-hexafluorpropylene copolymers (FEP resins) and polyvinylidene fluoride. Polyvinyl fluoride is available in film form (Tedlar) with excellent weathering resistance. 

Fluorinated polymers, especially polytetrafluoroethylene (PTFE) and copolymers of tetrafluoroethylene (TFE) with hexafluoropropylene (HFP) and perfluorinated alkyl vinyl ethers (PFAVE) as well as other fluorine-containing polymers are well known as materials with unique inertness. However, fluorinated polymers with functional groups are of much more interest because they combine the merits of pefluorinated materials and functional polymers (the terms functional monomer/ polymer will be used in this chapter to mean monomer/polymer containing functional groups, respectively). Such materials can be used, e.g., as ion exchange membranes for chlorine-alkali and fuel cells, gas separation membranes, solid polymeric superacid catalysts and polymeric reagents for various organic reactions, and chemical sensors. Of course, fully fluorinated materials are exceptionally inert, but at the same time are the most complicated to produce. 

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. 

Block and graft copolymers were prepared by Akutin, Parlashke-vich, Kogan, Kalinina, and Menes (128) by the use of ultrasonics on solutions of fluorine containing polymers or polysiloxanes on one hand and polymethyl methacrylate, polyvinyl chloride, ethylcellulose on the other. 

V. Strehmel, B. Stiller, B. Strehmel, A. M. Sarker, and D. C. Neckers, Fluorinated Distyrylbenzenes Containing Copolymers for Photoinduced Formation of Anisotropic Materials as Photoalignment Layers for Liquid Crystals. In Photoinitiated Polymerization, Vol. 847, K. D. Belfield and J. V. Crivello, Eds., American Chemical Society, Washington, DC, 2003, p. 482. 

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