Polyethersulfone chemical structures

Many kinds of AEMs based on quatemized polymers containing a quaternary ammonium group have been developed and tested in ADAFC, such as polyethersulfone cardo (QPES-C) [205], polyetherketone cardo (QPEK-C) [206], poly (phthalazinone ethersulfone ketone) (QPPESK) [207], poly(arylene ethersulfone) (QPAES) [208-210], QPAES cross-linked with tetraphenylolethane glycidyl ether (QPAES/4EP) [210], poly (arylether oxadiazole) (QPAEO) [211], poly styrene-block-poly (e thy lene-ran-butylene)-block-poly styrene (QSEBS) [212], poly(vinyl alcohol) (QPVA) [213], poly(vinyl chloride) (QPVC) [214], and poly (vinylbenzyl chloride) (QPVBC) [215]. The chemical structures of some of these polymers are shown in Fig. 6.13. 

Table 1. Chemical Structures and Glass-Transition Temperatures (Tg) of Polysulfone, Polyethersulfone, and Polyphenylsulfone...

Alkaline Membrane Fuel Cells, Membranes, Fig. 3 Chemical structure of (a) quaternary ammonium polysulfone-based anion exchange membrane and (b) polyethersulfone-cardo-based anion exchange membrane... 

Because of its chemical structure, polyethersulfone exhibits excellent resistance to thermal-oxidative degradation. As Figure 5.226 shows, this behavior also applies... 

Fig. 13.4 Chemical structure and characteristics of polysulfone (PSu) polymers used for dialysis membranes. Its specific chemical characteristics are shown in the panel above. PSu- membrane dimensions are depicted in the centered panel, a capillary cross section, inner diameter 200 om, b cross section of the membrane wall the membrane is only 1 pm thick and backed by a rather open support structure of 39 pm that maintains mechanical stability, c view on the outer membrane surface area, showing its high porosity, d view on the rather smooth inner membrane surface area where pore sizes are between 1 and 3 nm. The lower panel shows the detaiied molecular structure of polysulfone (PSu) and polyethersulfone (PES)...

Polyethersulfone (PES) is an amorphous polymer and a high-temperature engineering thermoplastic. Even though PES has high-temperature performance, it can be processed on conventional plastic processing equipment. Its chemical structure is shown in Fig. 12.15. PES has an outstanding ability to withstand exposure to elevated temperatures in air and water for prolonged periods. 

Figure 32.1 Chemical structures of (a) polysulfone and (b) polyethersulfone and FTIR-ATR spectra of the commercial nanofiltration membranes NF45, NF270, and NTR7450. The spectra reveal that the membranes contain a polysulfone layer (Puro et al., 2006, with permission of IChemE s journals).

The aromatic sulfone polymers are a group of high performance plastics, many of which have relatively closely related structures and similar properties (see POLYMERS containing SULFUR, polysulfones). Chemically, all are polyethersulfones, ie, they have both aryl ether (ArOAr) and aryl sulfone (ArS02Ar) linkages in the polymer backbone. The simplest polyethersulfone (5) consists of aromatic rings linked alternately by ether and sulfone groups. 

Polyarylsulfones are a class of high-use temperature thermoplastics that characteristically exhibit excellent thermal-oxidative resistance, good solvent resistance, hydrolytic stability, and creep resistance (10). In 1965, Union Carbide announced a thermoplastic polysulfone based on dichlorodiphenylsulfone and bisphenol A (11). This polysulfone became commercially available in 1966 and was designated as Udel polysulfone. Since 1966, Imperial Chemical Industry (ICI), Minnesota Mining and Manufacturing (3-M), and Union Carbide have commercialized polyarylsulfones that contain only aromatic moieties in the polymer structure. These materials have been designated Vlctrex polyethersulfone (ICI), Astrel 360 (3-M), and Radel polyphenylsulfone (Union Carbide). 

In order to solve the problems that occurred with unmodified cellulosic membranes, synthetic membranes were developed. The first synthetic polymeric membrane was produced in the early 1970s. Since that time, various synthetic polymers such as poly-sulfone, polyamide, poly(methyl methacrylate), polyethersulfone, polyethersulfone/ polyamide have been used in the production of synthetic hemodialysis membranes [20,21]. Synthetic membranes have large mean pore size and thick wall structure. These properties provide high ultrafiltration rate, which is necessary for hemodialysis to be achieved with relatively low transmembrane pressures [20]. The main difference in synthetic and cellulosic membranes is the chemical composition of the membrane. Synthetic membranes are made from manufactured thermoplastics, while both modified and unmodified cellulosic membranes are prepared from natural polymers [20]. 

In 1972 ICI started market development of polyethersulfone, PES. This amorphous polymer has a of 225°C. Compared to PSU, it exhibits higher thermal stability, better chemical and solvent resistance, and improved toughness [27], The structure appears in Fig. 1.13. 

Polysulfone (PSU) (typical structure shown in Figure 5.7) and polyethersulfone (PES) (typical structure shown in Figure 5.8) are highly versatile engineering polymers that have been applied in a variety of applications, including gas separation, membrane filtration, pervaporation, and electrodialysis. They have excellent chemical and mechanical stability, a relatively high glass transition temperature, and are easily cast as films from common aprotic solvents such as l-methyl-2-pyrrolidone (NMP) [32] and A lV-dimethylacetamide (DMAc) [33]. PSU has most commonly been evaluated for DMFCs as a blend with other... 

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