Aromatic Poly ethers

PPO is difficult to process due to its high melt viscosity, its methyl groups are sensitive to oxidation above 150 °C and its synthesis is relatively expensive. Therefore, the commercialization of neat PPO was not much successful, but PPO showed the unusual property to be miscible with polystyrene. Hence, PPO mainly serves as reinforcing component of polystyrene, and these blends were and are commercialized by GE under the Trademark Noryl [96]. 

Another polyether, which was commercialized by the Dutch ENKA NV under the name Tenax is poly(2,6-dipheyl-l,4-phenylene oxide) [97]. This polyether has a significantly higher crystallinity, thermostability, and oxidative stability than PPO. It is a niche product produced in the form of films or fibers. In addition to the oxidation of phenols with O2 (catalyzed by Cu ions) several other methods were explored for the preparation of poly(phenylene oxide)s [98] (Formula 6.4, bottom). 

Syntheses and properties of PES s were explored in the 1960 s by Union Carbide (USA), 3 M Corp (USA), and ICl pic (UK) [99-101]. Nearly at the same time. Two quite different synthetic strategies were elaborated, namely a Friedel-Crafts type polysulfonylation process (see Formula 6.5) and a nucleophilic substitution of 4,4 - 

The most widely used PES seems to be Udel . This PES, based on bisphenol-A, was originally commercialized by Union Carbide around 1965. In 1977, Union Carbide also marketed a PES based on 4,4 -dihydroxybophenyl under the name Radel . Its production was taken over by AmocoCorp. in 1990. A similar PES was also commercialized by 3 M Corp. in 1967 under the trademark Astrel , but because of patent problems its production was abandoned in the late 1970 s, and the production rights were sold to Carborundum Corp. ICI had at first commercialized a PES named Victrex 2000P which had the structure outlined in the first line of Formula 6.5. Later a PES containing biphenyl units was commercialized under the name Victrex 720 P in competition to Radel . A patent war with Carborundum Corp. was solved in favor of ICI. Afterwards, Carborundum took a license of ICI and on the basis of the production rights purchased from 3 M continued the production of Astrel [102, 103]. 

PES s are amorphous materials, because the bond angle of the SO2 group is more than 10° smaller than that of the ether group (122-124°). Depending of the diphenol used as reaction partner of 4,4 -dichlorodiphenylsulfone the glass-transition may vary from 170 to 270 °C (see Table 6.5). PES s almost exclusively 

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Hexafluoroisopropylidene-unit-containing aromatic poly(ether ketone)s were first synthesized from an alkaline metal salt of Bisphenol AF (1) and 4,4 -difluoro-benzophenone.14 Cassidy and co-workers prepared hexafluoroisopropylidene-unit-containing poly(ether ketone)s by condensing 2,2-bis[4-(4-fluorobenzoyl)-phenyl]-l,l,l,3,3,3-hexafluoropropane (9) and 2,2-bis[4-(4-fluorobenzoyl)-phenyljpropane (10) with Bisphenol AF (1) or Bisphenol A (4) (Scheme 7).15 The reactions are nucleophilic aromatic displacements and were conducted in DMAc at 155- 160°C with an excess of anhydrous potassium carbonate. After 3 to 6 h of reaction, high-molecular-weight poly(ketone)s are obtained in high yields. 

Miller et al. [87,88] have described the synthesis of hyperbranched aromatic poly(ether-ketone)s based on monomers containing one phenolic group and two fluorides which were activated towards nucleophilic substitution by neighboring groups. The molecular weight and polydispersity of the formed po-ly(ether-ketone)s could be controlled by reaction conditions such as monomer concentration and temperature. The formed polymers had high solubility in common solvents such as THF. 

An example for the synthesis of poly(2,6-dimethyl-l,4-phenylene oxide) - aromatic poly(ether-sulfone) - poly(2,6-dimethyl-1,4-pheny-lene oxide) ABA triblock copolymer is presented in Scheme 6. Quantitative etherification of the two polymer chain ends has been accomplished under mild reaction conditions detailed elsewhere(11). Figure 4 presents the 200 MHz Ir-NMR spectra of the co-(2,6-dimethyl-phenol) poly(2,6-dimethyl-l,4-phenylene oxide), of the 01, w-di(chloroally) aromatic polyether sulfone and of the obtained ABA triblock copolymers as convincing evidence for the quantitative reaction of the parent pol3rmers chain ends. Additional evidence for the very clean synthetic procedure comes from the gel permeation chromatograms of the two starting oligomers and of the obtained ABA triblock copolymer presented in Figure 5. 

Colquhoum, H. M. Lewis, D. E Ben-Haida, A. Hodge, P. Ring-chain interconversion in high-performance polymer system. 2. Ring-opening polmerization-copolyetherification in the synthesis of aromatic poly(ether sulfones). Macromolecules 2003, 36, 3775-3778. 

In 1962, Bonner (14) at DuPont was the first one who reported the synthesis of wholly aromatic poly(ether ketone ketone)s (PEKK) by Friedel-Crafts acylation. Isophthaloyl chloride was condensed with diphenyl ether using nitrobenzene as solvent and aluminum trichloride as a catalyst. 

Gil, M., Ji, X., Li, X., Na, H., Hampsay, J., Lu, Y. (2004). Direct synthesis of sulfonated aromatic poly(ether ether ketone) proton exchange membranes for fuel cell applications. /. Membrane Sci. 234, 75-81. 

As a final example of the use of proton NMR invoking spin diffusion to study miscibility of polymer blends, the use of CRAMPS to remove proton dipolar coupling in a blend of an aromatic poly(ether-imid) (PEI), and a poly(aryl-ether-ketone) (PEEK), with detection of the magnetization of the C in the blend under high resolution conditions is cited [51]. Here, detailed information on the chemical composition of the phases present, as inferred from high resolution NMR of C, is linked to typical sizes of domains as reflected in spin diffusion of proton magnetization. 

The actual formation of hyperbranched material proceeds during the polymerization of 3,5-difluoro-4 -hydroxydiphenyl sulfone in the presence of 3,4,5-trifluorophenylsulfonyl benzene or tris(3,4,5-trifluorophenyl)phos-phine oxide as a core molecule. Cyclic oUgomers formed dining this polymerization contribute to a low-molecular-weight polymer ranging from 3400 to 8400 Dalton. A triazin-based AB2 monomer has also been described. This monomer is shown in Figure 7.8. A hyperbranched aromatic poly(ether sulfone) with sulfonyl chloride terminal groups has been prepared by the polycondensation of 4,4 -(m-phenylenedioxy)-bis-(benz-enesulfonyl chloride). The polymerization was carried out in nitrobenzene at 120°C for 3 h in the presence of a catalytic amount of FeCls. ... 

K. Matsumoto and M. Ueda. Synthesis of hyperbranched aromatic poly-(ether sulfone) with sulfonyl chloride terminal groups. Chem. Lett., 35 1196-1197,2006. 

B. Liu, G.P. Robertson, D.-S. Kim, M.D. Guiver, W. Hu, Z. Jiang, Aromatic poly(ether ketone)s with pendant sulfonic acid phenyl groups prepared by a mild sulfonation method for proton exchange membranes. Macromolecules 2007, 40(6), 1934-1944. 

ES404, an aromatic poly(ether sulfone) membrane of nominal MWCO (4000 Da)... 

The electrophilic route for the production of aromatic poly(ether ketone)s involves the use of Friedel-Crafts catalysts. AICI3 is used as a catalyst for the polymerization of /p-phenoxybenzoyl chloride as such, or p-phenoxybenzoyl chloride or terephthaloyl chloride and 1,4-diphenoxybenzene to give a PEK. A PEEK is obtained by the use of / -phenoxyphenoxybenzoyl chloride, respectively [8]. The process is carried out at low temperatures, such as 0-30 °C. Due to the heterogeneous nature of this reaction, generally undesirable lower molecular weight polymers are produced. 

The physical properties of PEEK are shown in Table 6.2. Unfilled PEEK has a light brownish color. Thermoplastic aromatic poly(ether ketone)s, such as PEEK, have melting points greater than 330 °C, and their service temperatures may exceed 260 °C. They exhibit high mechanical strengths, such as tensile strength greater than 85 MPa [17]. PEEK can be used permanently up to 250 °C, even in hot water or steam. 

Fahmy MM, Al-Ghamdi RE, Mohamed NA. Synthesis, characterization, and thermal stability of novel wholly para-oriented aromatic poly(ether-amide-hydrazide)s bearing pendant groups and their corresponding poly(ether-amide-l,3,4-oxadiazole)s. Polym Bull 2011 66(5) 609-25. 

D. S. Thompson, L. J. Markoski, J. S. Moore, I. Sendijarevic, A. Lee, A. J. McHugh, Synthesis and characterization of hyperbranched aromatic poly(ether imide)s with varying degree of branching. Macromolecules, 33, 6412-6415 (2000). 

T. Koley, P. Bandyopadhyay, A.K. Mohanty, S. Banerjee, Synthesis and characterization of new aromatic poly(ether imide)s and their gas transport properties, Eur. Polym. J. 49 (12) (2013)4212-4223. 

T.S. Jo, C.H. Ozawa, B.R. Eagar, L.V. Brownell, D. Han, C. Bae, Synthesis of sulfonated aromatic poly (ether amide)s and their application to proton exchange membrane fuel cells, J. Polym. Sci., Part A Polym. Chem. 47 (2) (2009) 485 96. 

P. Bandyopadhyay, D. Bera, S. Banerjee, Semifluorinated, organo-soluble new aromatic poly(ether amide)s synthesis, characterization and gas transport properties, J. Membr. Sci. 382 (1-2) (2011) 20-29. 

D. Bera, P. Bandy opadhyay, B. Dasgupta, S. Banerjee, Gas transport properties of new aromatic poly (ether amide) s containing cyclohex-ylidene moiety, J. Membr. Sci. 407 08 (2012) 116-127. 

S. Maji, S. Banerjee, N.C. Pradhan, Separation of benzene/cyclohexane mixture using semifluorinated aromatic poly(ether amide) membranes with and without cardo unit in the main chain, Sep. Purif. Technol. 70 (1) (2009) 128-135. 

H. Behniafar, M. Sedaghatdoost, New fluorinated aromatic poly(ether-amide)s derived from 2,2 -bis (3,4,5-trifluorophenyl)-4,4 -diaminodiphenyl ether and various dicarboxylic acids, J. Ruorine Chem. 132 (4) (2011) 276-284. 

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