Styrene copolymerization with divinylbenzene

The synthesis of the first polymer-supported chiral Mn-salen derivatives was reported independently by Sivaram171 and Minutolo.171-173 Different monomeric Jacobsen-type units, containing two polymerizable vinyl groups, were copolymerized with styrene and divinylbenzene to yield the corresponding cross-linked polymers as a monolithic compact block.174-176 The less mobile system (Figure 19) with no spacer between the aromatic ring and the polymer backbone is less enantioselective. 

Catalysts synthesized from crown ether monomers 61 and 62 by copolymerization with styrene and either p-divinylbenzene or p,p -divinylbiphenyl (63) are listed in Table 14 along with their relative activities for solid/solid/liquid reactions of potassium acetate with benzyl chloride (Eq. (13)) and potassium cyanide with 1,4-dichlorobutane (Eq. (14)) in acetonitrile 183). 

Salen ligands can be bound to different materials. The synthesis of polymer-bound chiral Mn(III) - salen complexes was independently reported by Sivaram et al. [41, 42] and Minutolo et al. [43]. Here, the monomeric units of the Jacobsen catalyst [44] were functionalized with two vinyl groups, which were copolymerized with styrene and divinylbenzene. 

Enantioselective addition of dialkylzinc reagents to simple ketones was promoted by Ti-based catalysts prepared from chiral ligands such as trans-1-arylsulfonylamino-2-(isobornylamino)cyclohexane derivatives [70, 71]. Chiral bissulfonamide monomer (167) was prepared and copolymerized with styrene and divinylbenzene to give polymer-supported chiral ligand (168) [72]. Polymeric chiral ligands (168) were tested in the enantioselective addition of diethylzinc to acetophenone in the... 

Scheme 7 Siloxane-modified divinylbenzene telomer and octamer before copolymerization with styrene and divinyl benzene to give a silicone rubber.

Kawabata and others [17-20] have explored the usefulness of macroporous resins that contain 1 (R = benzyl or ethyl) copolymerized with styrene and divinylbenzene in water-purification. They have found them to be particularly effective in removing bacteria (e.g. E. Coli, Salmonella typhimurium, and others) from water. They have also successfully used the protein, aspartase, immobiUzed on a resin much like the water purification material to effect quantitative conversion of ammonium fumarate to aspartate in a continuous flow bioreactor [21]. 

Yin et al. [73,74] prepared new microgel star amphiphiles and stndied the compression behavior at the air-water interface. Particles were prepared in a two-step process. First, the gel core was synthesized by copolymerization of styrene and divinylbenzene in diox-ane using benzoylperoxide as initiator. Microgel particles 20 run in diameter were obtained. Second, the gel core was grafted with acrylic or methacryUc acid by free radical polymerization, resulting in amphiphilic polymer particles. These particles were spread from a dimethylformamide/chloroform (1 4) solution at the air-water interface. tt-A cnrves indicated low compressibility above lOmNm and collapse pressnres larger than 40 mNm With increase of the hydrophilic component, the molecnlar area of the polymer and the collapse pressure increased. 

C13-0110. Copolymerization of styrene with a small amount of divinylbenzene gives a cross-linked polymer that is hard and insoluble. Draw a picture of this polymer that shows at least tw o cross-links. 

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... 

In the early days of polymer science, when polystyrene became a commercial product, insolubility was sometimes observed which was not expected from the functionality of this monomer. Staudinger and Heuer [2] could show that this insolubility was due to small amounts of tetrafunctional divinylbenzene present in styrene as an impurity from its synthesis. As little as 0.02 mass % is sufficient to make polystyrene of a molecular mass of 2001000 insoluble [3]. This knowledge and the limitations of the technical processing of insoluble and non-fusible polymers as compared with linear or branched polymers explains why, over many years, research on the polymerization of crosslinking monomers alone or the copolymerization of bifunctional monomers with large fractions of crosslinking monomers was scarcely studied. 

Polystyrene is presently the overwhelming choice as the polymer support [Frechet and Farrall, 1977 Frechet et al., 1988 Messing, 1974]. The polystyrene used is a crosslinked polymer prepared by copolymerization of styrene with divinylbenzene (DVB). (The divinyl-benzene is usually the commercially available mixture containing the meta and para isomers... 

Radical Copolymerization of Styrene with 1,4-Divinylbenzene in Aqueous Suspension (Crossiinking Copolymerization)... 

Dowex ion exchange resins include a range of anion and cation resins for multibed demineralization, mixed-bed condensate polishing, as well as nuclear and other specialty applications. Most Dowex resins are based on styrene copolymerized with divinylbenzene (DVB). According to Dow, styrene/DVB structures are the preferred matrices for ion exchange resins because... 

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... 

We are interested in the application of polymers as adsorbents, ion exchangers, fuel cells, and permeable materials. In this regard, the first resins with some of these properties were obtained by D Aleleio in 1944 based on the copolymerization of styrene and divinylbenzene. Unfunctionalized polystyrene resins cross-linked with divinylbenzene (Amberlite) are widely applied as adsorbents [191,192], In addition, the polystyrene-divinylbenzene resins functionalized with sulfuric acid (sulfonation) to create negatively charged sulfonic sites are applied as cation exchangers, and treated by chloromethylation followed by animation produce anionic resins [193,194],... 

Styrene can be copolymerized with many monomers. The following monomers can be used along with styrene in the manufacture of food contact materials a-methylsty-rcne, vinyltoluene, divinylbenzene, acrylonitrile, ethyleneoxide, butadiene, fumaric and maleic acid esters of the mono functional saturated aliphatic alcohols C1-C8, acrylic acid ester and methacrylic acid, maleic acid anhydride, methylacrylamide-methylol ether, vinylmethyl ether, vinylisobutyl ether. Styrene and/or a-methylstyrene and/or vinyltoluene should be the main mixture component in every case. 

Other trialkyltin-containing monomers such as 3-tributyltinstyrene (84), tributyltin methacrylate (85) and 4-[bis(trimethylstannyl)methyl]styrene (86) were also reported to homo- and copolymerise with styrene under radical conditions " In addition, 3-tributyltinstyrene (84) was copolymerised under radical conditions with ethyl acrylate, methyl methacrylate, vinyl acetate and acrylonitrile . A functional methacrylate-based polymer was prepared by the copolymerization of the triorganotin methacrylate monomer 87 with styrene and divinylbenzene . 

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. 

Polymer-supported TADDOL-Ti catalyst 79 prepared by chemical modification was poorly active in the Diels-Alder reaction of 3-crotonoyloxazolidinone with cyclo-pentadiene (Eq. 24) whereas polymeric TADDOL-Ti 81 prepared by copolymerization of TADDOL monomer 80 with styrene and divinylbenzene had high activity similar to that of the soluble catalyst. In the presence of 0.2 equiv. 81 (R = H, Aryl = 2-naphthyl) the Diels-Alder adduct was obtained in 92 % yield with an endolexo ratio of 87 13. The enantioseleetivity of the endo product was 56 % ee. The stability and recyclability of the catalyst were tested in a batch system. The degree of conversion, the endolexo selectivity, and the enantioseleetivity hardly changed even after nine runs. Similar polymer-supported Ti-TADDOLate 82 was prepared by the chemical modification method [99]. Although this polymer efficiently catalyzed the same reaction to give the (2R,2S) adduct as a main product, asymmetric induction was less than that obtained by use of a with similar homogeneous species. 

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. 

Similar to the case of styrene, the copolymers of alkylstyrenes and arylstyrenes are common. The copolymerization is done for the same purposes as for polystyrene, namely to improve/modify certain properties. Copolymerization with divinylbenzene is probably the most frequently utilized. This copolymerization improves mechanical resistance, decreases solubility, and improves thermal resistance. For example, thermal decomposition of poly(vinyltoluene-co-divinyl benzene) 10-50% DVB starts at a higher temperature than that of poly(vinyl toluene). The decomposition at 560° C generates C1-C4 hydrocarbons, benzene, toluene, ethylbenzene, styrene, ethyltoluene, a-methylstyrene, vinyltoluene, divinylbenzene, naphthalene, and ethylstyrene, with a distribution that varies with copolymer composition [71, 118]. 

An alternative approach involves the polymerization of a suitable tin-containing monomer, 4 and was recently employed by Angiolini and coworkers,33 with the preparation of grafted organotin carboxylates by copolymerization of triorganotin derivatives of p-vinylbenzoic acid (p-VBA) with styrene and 1,4-divinylbenzene. 

The copolymerization of styrene with divinylbenzene (DVB) is necessary in order to obtain the required stability of the resin. Upon adding divinylbenzene to styrene, the two functional groups of DVB crosslink two polystyrene chains with each other. Part of the resulting skeleton is depicted schematically in Fig. 3-3. The percentage of DVB in the resin is indicated as percent crosslinking . The degree of crosslinking determines the porosity of the resin, which is another characteristic for the classification of PS/ DVB resins. 

---