Polysulfones, structure

Poly(butene-l sulfone) (PBS), a sensitive, positive, electron beam resist, is highly sensitive to 185-nm radiation (Table 3.4) (9). However, PBS does not absorb above 200 nm, and the sensitization has not been successful. Incorporation of pendant aromatic rings into the polysulfone structure extends the photosensitivity to the DUV and mid-UV regions (72). Himics and Ross (73) reported that carbonyl-containing poly(olefin sulfones) such as poly(5-hexen-2-one sulfone) are sensitive to UV-induced degradation and... 

The EIS characterization of the polysulfone-polyamide/PEG membranes was carried out not only to determine separately the contribution of the porous support and the PEG-modified top layer, but also to correlate the electrical changes with the PEG content. Eigure 2.5a shows an SEM micrograph of the cross section of the PS/PA-PEG membrane the porous polysulfone structure and the dense polyamide top layer where the PEG is mainly located can be clearly observed in this figure (Benavente et al. 2005). 

In the first stage, up to 10% of carbon is removed with carbon oxides. Relation of this percent to the content of anomalous structures in the polymer indicates that different structure degree is too high, much higher than the sensitivity of spectral methods. Meanwhile, preliminary analyses of studied thermoresistant polymeric materials (TP) showed their correspondence to postulated formulae, i.e. PSF corresponds to bisphenol A-derived polysulfone structure, PAl corresponds to fatty-aromatic polyimide derived fi om PPA and dodecamethylene diamine, etc. 

Koros W. J., Story B. J., Jordan S. M., O brien K. and Husk G. R., Material Selection Considerations for Gas Separation Processes, Polym. Engg. and Sci., 1987, 27, 603-610. Ghosal K. and Chern R. T., Aryl-nitration of Poly (phenylene oxide) and Polysulfone. Structural Characterization and Gas Permeability, J. Membr. Sci., 1992, 72, 91-97. 

Ghosal K. T., and Chern R. T., Aryl-nitration of Poly (phenylene oxide) and Polysulfone Structural Characterization and Gas Permeability, J. Membr. Sci., 1992, 72, 91-97. 

Many engineering thermoplastics (e.g., polysulfone, polycarbonate, etc.) have limited utility in applications that require exposure to chemical environments. Environmental stress cracking [13] occurs when a stressed polymer is exposed to solvents. Poly(aryl ether phenylquin-oxalines) [27] and poly(aryl ether benzoxazoles) [60] show poor resistance to environmental stress cracking in the presence of acetone, chloroform, etc. This is expected because these structures are amorphous, and there is no crystallinity or liquid crystalline type structure to give solvent resistance. Thus, these materials may have limited utility in processes or applications that require multiple solvent coatings or exposures, whereas acetylene terminated polyaryl ethers [13] exhibit excellent processability, high adhesive properties, and good resistance to hydraulic fluid. 

Using 4,4,-bis(4-hydroxyphenyl)pentanoic acid (BHPA)196 197 as comonomer, some polysulfones with pendent carboxylic groups were successfully synthesized.198199 Table 6.1 shows the structure of BHPA. The functional groups can be used for the preparation of graft copolymers. 

See also PBT degradation structure and properties of, 44-46 synthesis of, 106, 191 Polycaprolactam (PCA), 530, 541 Poly(e-caprolactone) (CAPA, PCL), 28, 42, 86. See also PCL degradation OH-terminated, 98-99 Polycaprolactones, 213 Poly(carbo[dimethyl]silane)s, 450, 451 Polycarbonate glycols, 207 Polycarbonate-polysulfone block copolymer, 360 Polycarbonates, 213 chemical structure of, 5 Polycarbosilanes, 450-456 Poly(chlorocarbosilanes), 454 Polycondensations, 57, 100 Poly(l,4-cyclohexylenedimethylene terephthalate) (PCT), 25 Polydimethyl siloxanes, 4 Poly(dioxanone) (PDO), 27 Poly (4,4 -dipheny lpheny lpho sphine oxide) (PAPO), 347 Polydispersity, 57 Polydispersity index, 444 Poly(D-lactic acid) (PDLA), 41 Poly(DL-lactic acid) (PDLLA), 42 Polyester amides, 18 Polyester-based networks, 58-60 Polyester carbonates, 18 Polyester-ether block copolymers, 20 Polyester-ethers, 26... 

Membranes UF membranes consist primarily of polymeric structures (polyethersulfone, regenerated cellulose, polysulfone, polyamide, polyacrylonitrile, or various fluoropolymers) formed by immersion casting on a web or as a composite on a MF membrane. Hydrophobic polymers are surface-modified to render them hydrophilic and thereby reduce fouling, reduce product losses, and increase flux [Cabasso in Vltrafiltration Membranes and Applications, Cooper (ed.). Plenum Press, New York, 1980]. Some inorganic UF membranes (alumina, glass, zirconia) are available but only find use in corrosive applications due to their high cost. 

Sulfur dioxide was the major volatile product and was used as a probe to correlate the radiation resistance with polymer structure. The use of biphenol in the polymer reduced G(SO ) by 60% compared with bisphenol A based systems (Bis-A PSF). Surprisingly, the isopro-pylidene group was shown to be remarkably radiation resistant. The ultimate tensile strain decreased with dose for all polysulfones investigated and the rate of decrease correlated well with the order of radiation resistance determined from volatile product measurements. The fracture toughness (K ) of Bis-A PSF also decreased with irradiation dose, but the biphenol based system maintained its original ductility. 

Fig. 1 Chemical structures of the polymers commonly used for preparation of beads poly (styrene-co-maleic acid) (=PS-MA) poly(methyl methacrylate-co-methacrylic acid) (=PMMA-MA) poly(acrylonitrile-co-acrylic acid) (=PAN-AA) polyvinylchloride (=PVC) polysulfone (=PSulf) ethylcellulose (=EC) cellulose acetate (=CAc) polyacrylamide (=PAAm) poly(sty-rene-Wocfc-vinylpyrrolidone) (=PS-PVP) and Organically modified silica (=Ormosil). PS-MA is commercially available as an anhydride and negative charges on the bead surface are generated during preparation of the beads...

Small-pore zeolite Nu-6(2) has a NSI-type structure and two different types of eight-membered-ring channels with limiting dimensions of 2.4 and 3.2 A [54]. Gorgojo and coworkers developed mixed-matrix membranes using Nu-6(2) as the dispersed zeolite phase and polysulfone Udel as the continuous organic polymer phase [55]. These mixed-matrix membranes showed remarkably enhanced H2/ CH4 selectivity compared to the bare polysulfone membrane. The H2/CH4 selectivity increased from 13 for the bare polysulfone membrane to 398 for the Nu-6(2)/ polysulfone mixed-matrix membranes. This superior performance of the Nu-6(2)/ polysulfone mixed-matrix membranes is attributed to the molecular sieving role played by the selected Nu-6(2) zeoHte phase in the membranes. 

These types of separators consist of a solid matrix and a liquid phase, which is retained in the microporous structure by capillary forces. To be effective for batteries, the liquid in the microporous separator, which generally contains an organic phase, must be insoluble in the electrolyte, chemically stable, and still provide adequate ionic conductivity. Several types of polymers, such as polypropylene, polysulfone, poly(tetrafluoroethylene), and cellulose acetate, have been used for porous substrates for supported-liquid membranes. The PVdF coated polyolefin-based microporous membranes used in gel—polymer lithium-ion battery fall into this category. Gel polymer... 

Various noncellulosic thln-film-composlte membranes were examined by scanning electron microscopy (SEM). Figure 3 illustrates the type of surface structure and cross-sections that exist in these membranes. Figure 3a shows the surface microporosity of polysulfone support films. Micropores in the film were measured by both SEM and TEM typically pore radii averaged 330 A. Figure 3b is a photomicrograph of a cross-section of a NS-lOO membrane. 

Figure 3a. SEM photomicrographs of composite membranes surface structure of microporous polysulfone support material.

A prominent class of poly(aryl ethers) is the sulfone-containing poly(aryl ethers) that is, poly(arylene ether sulfones), or polysulfones (PSF), and their sulfonated derivatives. The structure of a typical sulfonated polysulfone (SPSF) repeat unit is... 

This paper has provided the reader with an introduction to a class of polymers that show great potential as reverse osmosis membrane materials — poly(aryl ethers). Resistance to degradation and hydrolysis as well as resistance to stress Induced creep make membranes of these polymers particularly attractive. It has been demonstrated that through sulfonation the hydrophilic/hydrophobic, flux/separation, and structural stability characteristics of these membranes can be altered to suit the specific application. It has been Illustrated that the nature of the counter-ion of the sulfonation plays a role in determining performance characteristics. In the preliminary studies reported here, one particular poly(aryl ether) has been studied — the sulfonated derivative of Blsphenol A - polysulfone. This polymer was selected to serve as a model for the development of experimental techniques as well as to permit the investigation of variables... 

The Study of the Structure and Chain Dynamics of Polysulfones by Carbon-D NMR... 

Union Carbide, in 1976, made available a second generation polysulfone under the trade name Radel. Radel was formed from the reaction of a bisphenol and bis(p-chlorophenyl) sulfone (structure 4.76). This polysulfone exhibits greater chemical and solvent resistance, greater Tg of 220°C, greater oxidative stability, and good toughness in comparison to Udel. 

Ring-opening polymerization of 1,2-thiazetidines, because of their highly strained ring structure, is often investigated for eventual technological applications. Imai et al. have produced a new class of polyamide-polysulfon-amide, using this technique. 4,4-Dimethyl-l,2-thiazetidin-3-one 1,1-dioxide... 

An alternative approach towards improving the etch resistance of polysulfone polymers was reported by workers at RCA (80) for polysulfones based on vinyltrimethylsilane. These resists have the structure... 

The presence of aromatic groups in polymers greatly reduces their radiation sensitivity. Aromatic polysulfones are commercially important engineering plastics with high temperature resistance and also show good radiation resistance (16). Development of polymers with improved radiation resistance should be possible by copolymerization of other aromatic structures into the chain. 

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