Perfluorinated polyethers

Materials of this type have been sold by Du Pont Co. under the Freon E and Krytox trademarks. Perfluorinated materials stmcturaEy similar to those in equation 11 have been prepared by Ausimont by the low temperature irradiation of either hexafluoropropylene or tetrafluoroethylene with oxygen followed by heating and/or irradiation and have been sold as Fomblin Hquids (52). An isomeric polyether, Demnum, prepared by the oligomerization of 2,2,3,3-tetrafluorooxetane followed by fluorination has been commercialized by Daikin (eq. 12). 

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). 

Figure 3.10 shows the secondary ion spectra recorded from within the defect and its surroundings. The spectrum from the defective area clearly shows the presence of a polluting perfluorinated polyether structure (the C Fy peaks and the peak at mass 47 amu (CFO" ) are diagnostic of the polyether structure). 

Other SSIMS studies of polymer surfaces have included perfluorinated polyether [3.21], low-density polyethylene [3.22], poly(ethylene terephthalate) [3.23], and the oxidation of polyetheretherketone [3.24]. 

The technique now called fluorous biphasic catalysis was apparently first described in the Ph.D. thesis of M. Vogt in 1991 however, these studies did not become known to the community until sometime later. W. Keim, M. Vogt, P. Wasserscheid, B. Driessen-Holscher, Perfluorinated polyethers for the immobilization of homogeneous nickel catalysts , J. Mol. Catal A Chem. 1999,139,171. 

Fig. 20 Cryo-TEM image of isolated micelles and segmented rods made from miktoarm ABC block copolymers containing PEO, PB and perfluorinated polyether blocks (scale bar is 50 nm). A schematic representation of the stacking of block copolymer chains in segmented worms is also shown. Reprinted with permission from [284], Copyright (2004) American Association for the Advancement of Science...

Membrane research is a rather diverse field, exploiting perfluorinated iono-mers, hydrocarbon and aromatic polymers, and acid-base polymer complexes. Polyether and polyketo polymers with statistically sulfonated phenylene groups such as sPEK, sPEEK, and sPEEKK or polymers on the basis of benzimidazole have been tested as well. Recent reviews on membrane synthesis and experimental characterization can be found in the literature. ... 

To demonstrate further the powerful utiHty of the fluorous/organic biphasic approach to catalyst recycling, a dendrimer-encapsulated catalyst (DEC) with covalently attached perfluorinated polyether chains was synthesized [17] and metallic nanoparticles were introduced into the interior. 

Fig. 24. Synthetic scheme for the introduction of metallic nanoparticles into perfluorinated polyether chain derivatized poly (propylene imine) PPI dendrimers. Reprinted with permission from Ref. 100 Copyright 2000 WUey-VCH...

As discussed in the previous section, perfluorinated polyether pony-tails can be covalently grafted onto PPI dendrimers, and it has previously been shown that such materials are soluble in liquid CO2 [17]. HRTEM confirms that particles prepared within such dendrimer templates are nearly mono-disperse and are of a size that is consistent with the dendrimer template (Sect. 2.5.4). Such dendrimer-encapsulated metal particles are quite soluble in liquid and SC CO2. 

The production of perfluorinated polyethers 2 (nickel electrodes electrolyte anhyd HF current density 0.5-4 A dm-2 voltage 4-9 V temperature 10-20 C) is possible by electrochemical fluorination of the corresponding non-fluorinated polyethers l.37... 

A series of functionalized alkenes has been subjected to selective epoxidation reactions. Oxidation of perfluorinated vinyl polyethers by bubbling oxygen through the liquid that contains a catalytic amount of a Lewis acid, e.g. antimony(V) fluoride, results in the formation of acid fluorides together with a smaller amount of C = C bond cleavage.76 Perfluorinated pentaaIkyI-2.3-dihydrofuran 38, an example of an unsaturated cyclic ether that is quite stable owing to perfluoroalkylation. is epoxidized by hypochlorite to the product 39 at 45 C.62... 

Three series of products are used as lubricants silicone-oils or polytrifluoro-propyl methyl siloxane (Silastic 15-53 produced by the Dow Corning Company), perfluorinated polyethers (Fomblin, Montedison now Ausimont Company) and Kel F oils (3 M Company). Only these latter ones are obtained directly by telomerisation. 

D. E. Fowler, R. D. Johnson, D. van Leyen, and A. Benninghoven, Quantitative time-of-flight secondary ion mass spectrometry of a perfluorinated polyether, Surf. Inteif. Anal. 17, 125—136 (1991). 

I. A. Bletsos, D. Fowler, D. van Leyen, A. Benninghoven, and D. M. Hercules, Time-of-flight secondary ion mass spectrometry of perfluorinated polyethers, Anal. Chem. 62, 1275-1284 (1990). 

In the same way, Cook [87] obtained polyethers from perfluorinated dienes and fluorinated diols in an alkali medium according to the following scheme ... 

Halogenated perfluorinated aromatics were used [86] but the obtained polyethers exhibit Tg s greater than the previous ones ... 

Small heterocycles are of interest in view of their high reactivity and role in biosynthesis. Moreover, for the three-membered ring with an oxygen atom, the ease of ring cleavage creates conditions for polycondensations and heterocyclizations. The former give perfluorinated polyethers with a broad spectrum of practical applications, and the latter affords various heterocyclic compounds. 

The Perfluorinated Polyether Oils (PFPE). These oils are the most expensive oils available. They are extremely nonreactive, do not form tars, do not break down, are nonflammable, and can therefore be used in pumping pure oxygen. 

The potassium salt 226a has been found to react with pentafluorochloro-acetone. Subsequent treatment with KF and excess of pentafluorochloro-acetone yields perfluorinated polyethers 228 (167). 

A wide range of fluids with similar physical and chemical properties, including linear and cyclic perfluoroalkanes, linear and cyclic perfluoroethers and polyethers, perfluorotertiary amines and, in a few instances, perfluoroalkylhalides, may be considered to be perfluorinated or fluorous . Solvents within these categories are marketed around the world under a series of brandnames (Table 1). In certain instances, the commercial fluids represent mixtures of similar compounds with... 

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