Poly aryl ether ketone s

Poly(aryl ether ketones) belong to the class of engineering polymers. In early to mid-1970s, Raychem Corp. commercially introduced a poly-Caryl ether ketone) called Stilan . In this polymer, each ether and keto group is separated hy 1,4-phenylene units. In 1978, Imperial Chemical Industries PLC (ICI) commercialized a poly(aryl ether ketone) under the trademark Victrex PEEK.  

Still other somewhat refined varieties include the poly(ether ketone ketone) (PEKK), poly(ether ether ketone ketone) (PEEKK) and poly(ether ketone ether ketone ketone) (PEKEKK) polymer type.  

Poly(ether) Poly(ketone) Poly(ester) 

Poly(poly(ether)ketone) Poly(poly(ether)ester) 

Nucleophilic Route Hydroxy Functional Monomer Halogen Functional Monomer 

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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... 

Aromatic poly(aryl ether ketone)s containing 1,4-naphthalene moieties were prepared by the reaction of a bisphenol and 2 in the presence of potassium carbonate in DM Ac at 160°C as depicted in Scheme 3. A typical polymerization was carried out as follows To a 100-ml round-bottom flask was added 8.32 g (O.OlOmol) of2, 3.36g (O.OlOmol) of4,4 -(hexafluoroisopropylidene) diphenol, 51.2 g ofDMAc, and 3.1 g (0.022 mol) of potassium carbonate. The mixture was heated to 160°C with stirring under nitrogen for 18 h. The mixture was allowed to cool to room temperature. The polymer was precipitated by pouring the reaction mixture into a blender containing about 100 ml of water, filtered, washed three times with water and dried to yield 8.1 g (92% yield) as a white powder. 

Polycondensation reactions of 2 with diphenols were carried out in DMAc at 160°C using an excess of potassium carbonate to yield viscous solutions ofthe desired poly(aryl ether ketone)s. Judging by the viscosity increase, the polymerization reaction was near completion after only about 8h at 160°C. Aqueous... 

Scheme 3. synthesis of fluorinated poly (aryl ether ketone )s 3-7... 

Poly(arylether ketone), conducting, 7 524 Poly(aryl ether ketone)s, sulfonation reaction of, 23 717-718 Poly(di-n-alkylsilanes), thermochromic materials, 6 619... 

Xing, P., Robertson, G. R, Guiver, M. D., Mikhailenko, S. D. and Kaliaguine, S. 2004. Sulfonated poly(aryl ether ketone)s containing the hexafluoroisopro-pylidene diphenyl moiety prepared by direct copolymerization, as proton exchange membranes for fuel cell application. Macromolecules 37 7960-7967. 

Fig. 8 Chemical structures of fluorinated poly(aryl ether ketone)s...

Acyl cations are involved as propagating species in the synthesis of poly-(ether ketone)s. Poly (ether ketone)s are a class of thermoplastic crystalline polymers that have many desirable properties that make them useful as high-performance engineering materials [153,154]. The poly(ether ke-tone)s with the most useful properties are actually para-linked poly(aryl-ether ketone)s (PAEKs). They have excellent chemical resistance to oxidation and hydrolysis, high thermal stability, and many useful mechanical properties. Unlike some other materials with similar properties they are readily melt processable using conventional equipment. In addition, their mechanical properties are not affected deleteriously by most solvents. These polymers are usually crystalline. PAEKs contain arene groups joined by ether and carbonyl linkages. For example, two commercial poly-(ether ketone)s are PEK and PEEK (Fig. 36). 

Poly(aryl ether ketone)s have aromatic groups and both the ether group and the keto group are in the backbone. Figure 6.1 illustrates the basic repeating structures of this class of substances. Of course, there are several varieties of those structures shown in Figure 6.1, resulting from the use of comonomers, etc. A special related class is that of poly(ethersulfone). 

Blends of poly(aryl ether ketone)s and certain poly(amide imide)s and poly(imide)s (PI)s are highly compatible. They tend to form one phase in the amorphous state, and thus are miscible systems. As a result, such blends significantly improve the processability of the poly(amide imide) or the PI material. Further, by increasing its Tg, the ultimate use temperature of the poly(aryl ether ketone) is significantly increased. ... 

In the course of melt processing, unstabilized poly(aryl ether ketone)s show a strong tendency to crosslink. This behavior is highly undesirable since the melt viscosity increases and the polymer properties suffer. As the exposure time in the melt lengthens, melt fabrication becomes progressively more difficult. 

Poly(aryl ether ketone)s show outstanding chemical resistance and thermal properries. They are virtually insoluble in all conunon solvents at room temperature. These properties make poly(aryl ether ketone)s attractive materials for porous membrane preparation. 

However, the application of poly(aryl ether ketone)s in membrane fabrication has been limited owing to their intractability, which prevents the use of conventional solvent-based methods of membrane casting. Several routes are known for the preparation of poly(aryl ether ketone) membranes. 

Poly(aryl ether ketone)s 223 Table 6.6 Solubility of PEEK in Various Solvents" ... 

Other compounds are triphenyl phosphate and substituted derivatives, such as tricresyl phosphate [31]. However, it has been suggested that, due to their high vapor pressure, these compounds might escape from the melt at the processing temperature customary for poly(aryl ether ketone)s, which can lead to odor nuisance and, in the case of injection molding, to coatings forming on the mold surface. For this reason, less volatile stabilizers have been proposed [32]. 

The phosphonite type is much less effective than the phosphite type in the stabilization of poly(aryl ether ketone)s. However, the addition of organic phosphorus compounds in conjunction with an organic acid, such as oxalic acid or acetic acid, results in a very significant reduction in melt viscosity, even where the phosphorus compound alone has a detrimental effect. 

Poly(aryl ether ketone)s with two quaternary ammonium groups on pendant phenyls can be synthesized by a bromination followed by a quatemization reaction with trimethylamine [72]. Such polymers play an important role in the preparation of direct methanol fuel cells. 

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