Aromatic poly ether sulfone

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. 

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. 

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

In another attempt double bond side functionalities were introduced onto pyridine-based aromatic poly(ether sulfone)s. The ultimate scope of this approach was the cross-linking of the active double bonds after polymerization and after the preparation of the desired polyelectrolyte membranes in order to mechanically and thermally stabilize the doped membranes, as will be described below in greater detail. 

Ueda, M., Toyota, H., Ouchi, T., Sugiyama, J.I., Yonetake, K., Masuko, T., Teramoto, T. (1993) Synthesis and characterization of aromatic poly(ether sulfone)s containing pendant sodium sulfonate groups. Journal of Polymer Science Part A Polymer Chemistry, 31, 853-858. 

Takeuchi, M., Jikei, M., Kakimoto, M. (2003) Preparation of hyperhranched aromatic poly(ether sulfone)s possessing sulfonic acid terminal groups for polymer electrolyte. Chemistry Letters, 32, 242-243. 

Further interesting findings resulted from syntheses of aromatic poly(ether sulfone)s [64, 65]. The fraction of cycles increased at the expense of linear chains with increasing conversions. Due to the lower reactivity, 4,4 -dichlorodiphenyl sulfone yielded lower molar masses than 4,4 -difluorodiphenyl sulfone, with the consequence that the fraction of cycles was lower. Poly(ether sulfone)s derived from tert-butyl catechol ((d) in Formula 7.3) proved to be particularly well suited to MALDI-TOF mass spectrometry. The poly ether with the highest molar mass gave a spectmm showing mass peaks of cycles up to 20 kDa. After fractionation mass peaks of cyclic polyethers up to 27 kDa were achieved and no signals of linear chains were detectable. However, the fraction above 27 kDa certainly contained linear chains, because in a real experiment 100 % conversion without any side reaction cannot be achieved. The formation of cyclic polyethers in syntheses of poly(benzonitrile ether)s (e.g. (a) in Formula 7.4), of poly(pyridine ether)s ((b) in Formula 7.4) and of poly(ether ketone)s was also screened by MALDI-TOF mass spectrometry [66-68]. 

Other coupling reactions were also employed to prepare poly(arylene etherjs. Polymerization of bis(aryloxy) monomers was demonstrated to occur in the presence of an Fe(III) chloride catalyst via a cation radical mechanism (Scholl reaction).134 This reaction also involves carbon-carbon bond formation and has been used to prepare soluble poly(ether sulfone)s, poly(ether ketone)s, and aromatic polyethers. 

Another concern for polystyrene- and some aromatic-based PEMs is hydrolysis of fhe sulfonic acid group from aromatic rings as well as hydrolytic cleavage of polymer backbone under fuel cell conditions for aromafic polymers including polyimides, poly(arylene ethers), poly(ether ketones), and poly(ether sulfones). It is well known that the sulfonation of aromafic rings is a reversible process especially at low pH and at elevated temperature (Scheme 3.3). The reversibility of sulfonation, for example, is used in fhe preparafion of trinitrotoluene or picric acid. Por the simplest membrane of the class of arylsulfonic acids (i.e., benzenesulfonic acid), fhe reacfion occurs upon freatment with a stream of superheated steam at 180°C.i ... 

Most of today s ultrafiltration membranes are made by variations of the Loeb-Sourirajan process. A limited number of materials are used, primarily polyacrylonitrile, poly(vinyl chloride)-polyacrylonitrile copolymers, polysulfone, poly(ether sulfone), poly(vinylidene fluoride), some aromatic polyamides, and cellulose acetate. In general, the more hydrophilic membranes are more fouling-resistant than the completely hydrophobic materials. For this reason water-soluble... 

Aromatic polyethers, including poly(ether sulfone)s and poly(ether ke-tone)s, have been synthesized by the Scholl reaction. In the Scholl reaction a Friedel-Crafts catalysts is used to effectuate the coupling of two aromatic groups to form an aryl-aryl bond, accompanied by the elimination of two aromatic hydrogens [Eq. (58)] [188-190]. This reaction proceeds under oxidative reaction conditions by a cation-radical mechanism [191,192]. 

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. 

Poly(ether sulfones) containing aromatic rings in the backbone have much better thermal stability compared to poly(sulfur dioxide-co-alkenes). For example, PSF degrades very slowly in vacuum above 400° C, and only above 460° a more rapid decomposition begins [4], Other poly(ether sulfones) behave similarly [5]. Several reports on the thermal decomposition for poly(ether sulfones) are available in literature. A summary of such reports are given in Table 12.2.3. 

T. Yokozawa, T. Taniguchi, Y. Suzuki, and A. Yokoyama. Chain-growth polycondensation of monomer consisting of two aromatic rings Synthesis of well-defined poly(ether sulfone) from 4-fluoro-4 -hydroxydiphenyl sulf-one. J. Polym. ScL, Part A Polym. Chem., 40 3460-3464, 2002. 

In addition to the polymers described above, the MALDI technique has also been employed for the characterization of several synthetic polymeric materials. The literature reports the MALDI characterization of polyacrylonitrile (PAN), poly(ether sulfone) (PES), poly(dimethyl phenylene oxide) (PDMPO), and functionalized poly(p-phenylene)s. Analysis by MALDI-TOF of aromatic polyethers (such as PEEK), can be found, and several macrocyclic samples were also characterized by MALDI-TOF. ... 

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. 

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(ether sulfone). 

Yokozawa T, Taniguchi T, Suzuki Y, Yokoyama A. Chain-growth polyconden sation of monomer consisting of two aromatic rings synthesis of well-defined poly (ether sulfone) from 4-fluoro-4 -hydrox ydiphenyl sulfone. J Polym Sci Part A Polym Chem 2002 40 3460-4. 

A new aromatic diamine monomer with four pendant -CF3 groups was successfully synthesized by a three-step reaction using w(4-fluorophenyl)sulfone and A-bromosuccinimide as starting materials. Then, a series of fluorinated poly(ether sulfone imide)s was conveniently prepared from the diamine and three aromatic dianhydrides (BPDA, BTDA, and ODPA) via one-step solution polycondensation. 

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. 

The highly intractable chemical stmcture vMch. inq)arts the outstanding mechanical properties also makes the PATs very difficult to process (4, 5). In the ftilly imidized form PAI is not processable hence a poly(amic acid) (PAA) precursor is the usual form in which they are supplied and bricated. The precursors themselves have very hi viscosities in the melt state and hence the flow characteristics tend to be very poor. Semicrystalline and amorphous polyamides (6) and aromatic sulfone polymers such as poly(phenylene sulfide), poly(ether sulfone) and polysulfone (7) have been blended with the precursor to PAI, to obtain better flow characteristics. 

Polymers without CH bonds, e.g. poly(tetrafluoroethylene) (PTFE), or containing exclusively aromatic CH bonds, e.g. poly(ether ether ketone) (PEEK), poly(ether sulfone) (PES) and polyimides (PI), are stable to oxidation. 

The nucleophilic substitution reaction of an activated benzenoid halide with a phenoxide anion is currently the method used worldwide for the preparation of aromatic poly(aryl ether sulfones) " and poly(aryl ether ketones). " Amoco Performance Products UDEL Polysulfone and RADEL Polyphenylsulfone are made commercially via this route. The subject substitution reactions are also used by ICI to produce their Victrex Poly(ether sulfone) (PES) and Victrex Poly(ether ether ketone) (PEEK). 

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