Styrene-divinylbenzene copolymeric

The most commonly used resins are gel type sulfonated cation exchangers or anion exchangers with a quaternary ammonium functional group. The exchange capacity of the resins used is generally higher than those used for ion chromatography. The resins may be either styrene-divinylbenzene copolymeric beads or polyacrylate beads. The diameter of the beads should be small and uniform. Resins with a 5 pm bead diameter are now available. 

Kureshy developed a polymer-based chiral Mn-salen complex (Figure 21). Copolymerization of styrene, divinylbenzene, and 4-vinylpyridine generated highly cross-linked (50%) porous beads loaded with pyridine ligands at 3.8 mmol g-1. Once the polymer was charged with the metal complex catalyst, enantioselective epoxidation of styrene derivatives was achieved with ee values in the range 16 46%. 79... 

At present all commercial polystyrene (with average molecular weights between 100,000 and 400,000) is manufactured by radical polymerization, which yields atactic polymers.476 Peroxides and azo compounds are commonly used initiators. The suspension process (usually as a batch process in water at 80-140°C) produces a product with relatively high residual monomer content.223 More important is the continuous solution process (usually in ethylbenzene solvent at 90-180°C), which yields high-purity product. Styrene can be copolymerized with numerous other monomers.477 One of these copolymers, the styrene-divinylbenzene copolymer produced by free-radical polymerization, has a crosslinked stucture and is used in... 

This study was carried out in order to evaluate the applicability of extraction chromatography, with TBP as the extracting agent, instead o anion exchange for efficient purification of plutonium from Am (18,19). The resin used was Levextrel-TBP, a product of Bayer AG, Leverkusen, Germany. The Levextrels are styrene - divinylbenzene - based resins which are copolymerized... 

Stannic chloride has been attached to monomers 21 containing ester (21a), carbazole (21b), pyrrolidone (21c), nitrile (21d) and pyridine (21d) moieties. The polymeric ligands were prepared by copolymerization of styrene, divinylbenzene and functional monomers such as methyl methacrylate, A -vinylcarbazole, Af-vinylpyrrolidone, acrylonitrile and 4-vinylpyridine [33], These polymers were treated with stannic chloride in chloroform to afford the corresponding polymer-supported stannic chloride complexes (Eq. 8). These polymeric complexes have been used as catalysts for such organic reactions including esterification, acetalization, and ketal formation. These complexes had good catalytic activity in the reactions and could be reused many times without loss of activity. Their stability was much better than that of plain polystyrene-stannic chloride complex catalyst. 

Catalyzed enantioselective Mukaiyama-aldol reactions have been developed extensively [101] and chiral polymer-supported Lewis acids are the catalysts of choice. Polymer-supported chiral A(-sulfonyloxazaborohdinones 86 and 87, prepared by copolymerization of styrene, divinylbenzene, and chiral monomers derived from L-valine and L-glutamic acid, respectively, have been used for aldol reactions [102]. The rates of reaction using the polymeric catalysts were slow and enantioselectivity was lower than was obtained by use of the low-molecular-weight counterpart (88). The best ee obtained by use of the polymeric catalyst was 90 % ee with 28 % isolated yield in the asymmetric aldol reaction of benzaldehyde with 89 (Eq. 27). 

Monodisperse particles may also be produced with a cross-linked structure, and monodisperse porous particles may be obtained (Ugelstad et aL, 1980a) by applying methods known from suspension polymerization. Particles with functional surface groups have been prepared by chemical modification of the surface of cross-linked monodisperse particles of styrene-divinylbenzene or by copolymerization with monomers containing the desired functional groups. 

A copolymerization of styrene, divinylbenzene, and maleic anhydride was carried out in the presence of silica. This was hydrolyzed in boiling water, then treated with chloroplatinic acid to add platinum on silica.64 Presumably, the anhydride reacted with the hydroxyl groups on the surface of the silica. Then the platinum (II) formed a salt with some of the carboxyl groups. 

The cross-linked polymer 27 (cross-linker not represented) containing the HOSu residue for anchored DCC-promoted active ester formation was also obtained by copolymerization of N-acetoxymaleimide with styrene and divinylbenzene, followed by hydrolysis [102]. In addition, supported HOSu-active esters have been prepared by a method consisting of the synthesis of N-hydroxymaleimide esters of N-protected amino acids and subsequent copolymerization of these esters with styrene, divinylbenzene and 4-chlorophenylmaleimide [103]. 

K. Kusumoto, T. Sata and Y. Mizutani, Copolymerization of chloromethylstyrene and divinylbenzene in the absence or presence of poly(vinyl chloride), J. Macromol. Sci., Chem., 1987, A24, 645-659 Y. Kagiyama, K. Shikata and Y. Mizutani, Copolymerization of styrene-divinylbenzene in the presence of poly(vinyl chloride), J. Appl. Polym. Sci., 1979, 23, 1309-1318. 

GEL-TYPE STYRENE-DIVINYLBENZENE COPOLYMERS BY FREE RADICAL COPOLYMERIZATION... 

Porous solids were obtained by copolymerization of styrene-divinylbenzene [40,42] and cyclohexyl methacrylate-allyl methacrylate [41] in the continuous phase of microemulsions. Menger et al. [40] showed that the pore size of the material, always larger than the initial droplet size, is highly dependent on the water/surfactant ratio in the... 

E) F unctionalization of membranes - Membranes containing functional groups, which dominate their choice and use as reactive materials, are made by (a) polymerizing styrene-divinylbenzene in sheet-shaped molds followed by further chemical reactions for incorporation of the active species, (b) copolymerization of the functionalized monomer with divinylbenzene in thin film form, and (c) mechanically incorporating powdered functionalized polymer into a sheet of some other extrudable or moldable matrix [77-82]. 

TVEX synthesis is carried out in an agitated water-jacket reactor [4,5]. Once the reactor is loaded with a 0.5% starch solution as an emulsion stabilizer, the reaction mixture containing styrene, divinylbenzene (cross-linking agent), the extractant, and benzoyl peroxide as initiator of radical copolymerization is fed into the reactor at 50°C. After 8 honrs of polymerization, TVEX granules are obtained and then are washed with water and size classified. 

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