Polyether-ketone

Other backbone stmctures that have generated a great interest are the polyether ketones. An attempt was made to synthesize amino-terminated arylene ether ketones, which were subsequendy converted into the corresponding maleinhde-terrninated oligomers (26). The aim of this approach was to obtain tough, solvent-resistant, high temperature thermosets. 

Polyarylether Ketones. The aromatic polyether ketones are tme thermoplastics. Although several are commercially available, two resins in particular, poly ether ether ketone [31694-16-3] (PEEK) from ICI and poly ether ketone ketone (PEKK) from Du Pont, have received most of the attention. PEEK was first synthesized in 1981 (20) and has been well studied it is the subject of numerous papers because of its potential use in high performance aircraft. Tough, semicrystalline PEEK is prepared by the condensation of bis(4-fiuorophenyl) ketone with the potassium salt of bis(4-hydroxyphenyl) ketone in a diaryl sulfone solvent, such as diphenyl sulfone. The choice of solvent is critical other solvents, such as Hquid HE, promote the reaction but lead to premature low molecular-weight crystals, which do not exhibit sufficient toughness (21). 

Polyether ketone (PEK) (structure A). In 1986 three European companies (BASF, Hoechst and ICI) announced they were developing the material (to be marketed under the trade names of Ultrapek, Hostatec and Victrex PEK respectively). 

Polyether ketones were introduced in 1986. These materials have the highest operational temperatures of any thermoplastic material. 

Kiefer et al. (4) prepared proton-conductive electrolytes for use in fuel cells by free radically grafting vinyl-phosphonic acid and vinylsulfonic acid onto a polyether ketone substrate. 

EP 323142 (European) 1989 Ternary polyether ketone blend wire insulations Pirelli General PLC, UK CK Alesbury, RJ Murphy Formulation shows excellent stress craze resistance, flexibility and flame resistance Blends of polyarylene ether ketones, polyether imides and polyfimide siloxanes) were coated onto wire for solvent resistance, O index and abrasion resistance. Blends without siloxane-imide copolymer did not meet these properties... 

In addition to the polybenzimidazole blends with imide-siloxanes, it was also demonstrated that other different polyether imide-siloxane-segmented copolymers of variable composition could be used to modify semi-crystalline polyether ketones (PEEK) by presumably an analogous mechanism. The mechanical properties and transition temperatures of those systems have been reported [124,125], and would appear to be additional suitable candidates for the harsh outer space environment (see Table 4 and Fig. 21). 

Polyether ketones (PEEKs) are studied, but generally do not give performance advantages over Nation, although cost may be lower. Polyphenylene sulphonic acid membranes may improve performance at low humidity, and fluorinated polyarylene ethers may be produced at lower cost, but so far have low conductivity. Also, membranes based on bacterial cellulose with added precious metals have been investigated. Generally, hydrocarbon-based materials have lesser mechanical strength than the C-F based materials (Gil et ah, 2004 Lee et ah, 2004 Evans et ah, 2003). 

More tractable and potentially useful polyether ketones, incorporating phenylene-carborane-phenylene units, and with properties suitable for high temperature applications, have been prepared by acylation reactions (using trifluoromethanesulfonic acid as both medium and catalyst) between appropriate dicarboxylic acids and phenoxyphenylcarboranes. For example, the polyetherketone 20 (Scheme 3.6), derived from bis(4-phenoxyphenyl)-para-carborane and biphenyl-4,4 -dicarboxylic acid, is essentially amorphous on isolation from trifluoromethanesulfonic acid, but crystallizes when heated above its glass transition temperature (267°C) before hnally melting at about 390 0... 

There are also a few common polymers whose accepted names convey relatively little information about the repeating unit structure. The primary examples are polycarbonate, poly(phenylene oxide), polyamide-imides, poly-sulfones, and polyether ketones (see Table 1.3). 

IMI has also developed a general route for the synthesis of homo- and hetero-disubstituted benzophenones such as 4,4 -difluorobenzophenone (DFBP), 4,3 -di-fluorobenzophenone, and 4,4 -diphenoxybenzophenone (DPOBP). These substituted benzophenones are important materials, with a variety of uses as specialty monomers (for polyether ketones and polyarylene ether ketones) and pharmaceutical intermediates. These benzophenones are prepared by utilizing Heck technology in conjunction with an oxidative cleavage reaction. 

PTFE can be compounded with polymeric fdlers with adequate thermal stability. Examples of such polymers include polyarylates such as polyether-ketone, polyphenylene sulfone, and polyphenylene sulfide. Surface characteristics such as wear rate, coefficient of friction, and surface tension can be modified with these additives. 

To prepare new and inexpensive membranes, various trials have been made 196 sulfonated aromatic polyether membrane such as polyether ketones (PEEK),197 sulfonated polysulfone198 and membranes from sulfonated polyphenylene sulfide,199 phosphoric acid-doped polybenzimidazole, (PBI),200 polybenzimidazole having sulfonic acid groups,201 polybenzimidazole with phosphonic acid groups,202 a blend membrane of polybenzimidazole and sulfonated polysulfone,203 sulfonated phosphazene polymer.204... 

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