Perfluorinated polymers

Chemical Properties. A combination of excellent chemical and mechanical properties at elevated temperatures result in high performance service in the chemical processing industry. Teflon PEA resins have been exposed to a variety of organic and inorganic compounds commonly encountered in chemical service (26). They are not attacked by inorganic acids, bases, halogens, metal salt solutions, organic acids, and anhydrides. Aromatic and ahphatic hydrocarbons, alcohols, aldehydes, ketones, ethers, amines, esters, chlorinated compounds, and other polymer solvents have Httle effect. However, like other perfluorinated polymers,they react with alkah metals and elemental fluorine. 

A large variety of newer poly(ether imide)s has been described. Included among these are perfluorinated polymers (96), poly(ester ether imide)s (97), poly(ether imide)s derived from A/,Ar-diamino-l,4,5,8-naphthalenetetracarboxyHcbisimide (98), and poly(arylene ether imide ketone)s (99). In addition, many other heterocyHc groups have been introduced into polyether systems, eg, poly(pyrazole ether)s (100) and poly(aryl ether phenylquinoxaLine)s (101) poly(aryl ether oxazole)s with trifluoromethyl groups (102) and polyethers with other heterolinkages, eg, poly(arylether azine)s (103). 

The membrane, made from a perfluorinated polymer bearing sul-phonic acid groups, is known in the trade as Nafion . 

Perfluorinated polymers, 18 288-353. See also Perfluorinated ethylene-propylene (FEP) copolymers poly tetr afluoroethylene, 18 288—306 tetrafluoroethylene-ethylene copolymers, 18 316-329 tetrafluoroethylene-perfluorodioxole copolymers, 18 339-342 tetrafluoroethylene-perfluorovinyl ether, 18 329-339... 

Here we would like to emphasize that treatment with XeFj fluorinates the polymer surfaces, with the depth and degree of fluorination depending upon the reaction conditions. We never observed the formation of a perfluorinated surface layer after treatment with XeF,. Results of XPS analysis of XeFj-treated polyethylene film —(—CHj—CHj—) — showed that the maximum degree of fluorination corresponded to the composition —(—CF2—CH2—) —. After that, visible destruction of the polymer surface, i.e., cleavage of C—C bonds in the polymer macromolecule, would start. These results differ from those of the fluorination of polymer powders it was reported by Lagow and Margrave in the early 1970s that polymer powders were fully converted into perfluorinated polymers under the action of a F /N mixture. ... 

Figure 19. Transport coefficients of diverse membranes based on perfluorinated polymers and Nafion/...

Figure 20. Electro-osmotic drag coefficients of diverse membranes based on perfluorinated polymers (Dow - and Nafion/silica composites ) and polyarylenes (S—PEK/ PSU blends, ionically cross-linked S—PEK/PBP ), as a function of the solvent (water/methanol) volume fraction Xy (see text for references). Lines represent data for Nafion and S—PEK (given for comparison) for data points, see Figure 15. Dashed lines correspond to the maximum possible electro-osmotic drag coefficients for water and methanol, as indicated (see text).

Recently, a new type of diaphragm has impacted the industry for a few new plants. The new membranes are perfluorinated polymers with occasional sulfonate and/or carboxylate groups. They have the general structure outlined here. 

Table 2.1 lists a number of dioxole monomers and indicates their ability to homopolymerize and/or copolymerize with TFE in CFC-113 solution. The copolymerization of dioxoles with chlorine in the 4 and 5 position of the dioxole ring further demonstrates the very high reactivity of this ring system. Thus an almost infinite number of dioxole polymers can be prepared with one or more comonomers in varying proportions. We have chosen to focus our present work on copolymers of TFE and PDD to preserve the outstanding thermal and chemical properties of perfluorinated polymers. At this point it should be noted that fully fluorinated ethers are nonbasic and effectively possess the same chemical inermess as fluorinated alkanes. Perfluorinated ether groups in polymers are even less reactive as a result of their inaccessibility to chemical reagents. 

Like perfluorinated polymers, perfluorinated fluids are both chemically and thermally very stable. Originally developed during the Manhattan Project their commercial application dates from the 1960s. There are two major production methods, cobalt(III) fluoride fluorination of hydrocarbons and electrochemical fluorination. The first route involves the fluorination of a stirred or fluidized bed of cobalt(II) fluoride to cobalt(III) fluoride with elemental fluorine at... 

Diethyl phenylmalonate and its sodium salt undergo substitutive fluorination by perfluoro-1-fluoropiperidinc (1) and perfluorinated polymers. The fluorination product is diethyl fluoro(phenyl)malonate, perfluoro-l-fluoropiperidine being a more efficient fluorinating agent than the N-F containing fluoropolymers 5. 

Unsaturated fluoroethers form an extremely significant class of monomers which are used for improving the properties of perfluorinated polymers. Most of the dehalogenations have been carried out using zinc in protic or dipolar aprotic solvents (see Table 8). 

Nafion (17) is a perfluorinated polymer related to teflon (polytetrafluoroethylene). An electrode is conveniently coated by allowing an ethanolic solution of the polymer to evaporate. The film produced is stable, rather more so in fact than other polymer films, e.g. polyvinylpyridine (see Section 57.3.2.2). At the microscopic level the polymer separates into two phases, the bulk polymer and the lower density ionic cluster phase. Diffusion of ions can occur quite freely for example, the diffusion coefficient of Na+ in Nafion (MW 1200) is only slightly less than in water.44... 

Polymeric resin sulfonic acids including sulfonic acid resins complexed with Lewis acids and perfluorinated polymer resin acids (Nafion-H and Nafion-silica nanocomposites). 

A.2.2. Perfluorinated Polymer Resin Acids. A convenient solid perfluori-... 

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