Polystyrene divinyl benzene copolymers

Since the introduction of gel-permeation chromatography (GPC) in the 1960 s, there have been tremendous advances in polymer gel size-exclusion column technology. Polystyrene-divinyl benzene copolymer gels, and the techniques by which they are packed into columns, have improved to the point where commercial columns exhibit up to 50,000 plates/meter. These lO-ym gels are sufficiently rugged to permit flow rates of up to 3.0 ml/minute... 

Drinking water Preconcentration onto 5 pm C18-silica or 7 pm polystyrene-divinyl benzene copolymer with subsequent backflush onto analytical HPLC column. RP-HPLC/UV (254 mn) 0.03-0.06 pg/L (ppb) 91 ( 10% RSD) at sample volumes up to 300 mL Driss et al. 1993... 

Nonpolar interactions (hydrophobic) typical octadecyl-modified silica, polystyrene-divinyl benzene copolymers, or carbon-based sorbent. 

The plastic separating column was 7.5 x 100mm and was packed with a cation exchange resin in the H+ form TSK SCX 5pm (polystyrene divinyl benzene copolymer-based material with a high cation exchange capacity). 

Gel-Permeation Chromatography. A Water Associates HPLC with four Shodex GPC-AD-802S columns was used with dimethylformamide at a flow rate of 1 mL/minute. The gel is polystyrene-divinyl benzene copolymer and has exclusion limit of 8,000 by polystyrene molecular weight. Sample injection... 

Aromatic electrophilic substitution is used commercially to produce styrene polymers with ion-exchange properties by the incorporation of sulfonic acid or quaternary ammonium groups [Brydson, 1999 Lucas et al., 1980 Miller et al., 1963]. Crosslinked styrene-divinyl-benzene copolymers are used as the starting polymer to obtain insoluble final products, usually in the form of beads and also membranes. The use of polystyrene itself would yield soluble ion-exchange products. An anion-exchange product is obtained by chloromethylation followed by reaction with a tertiary amine (Eq. 9-38) while sulfonation yields a cation-exchange product (Eq. 9-39) ... 

Polystyrene and its divinylbenzene cross-linked copolymer have been most widely exploited as the polymer support for anchoring metal complexes. A large variety of ligands containing N, P or S have been anchored on the polystyrene-divinylbenzene matrix either by the bromination-lithiation pathway or by direct interaction of the ligand with C1-, Br- or CN-methylated polystyrene-divinyl-benzene network [14] (Fig. 7). 

Functionalization of crosslinked polymers by Mannich reaction" includes mainly polystyrenes and polyacrylics such as styrene/divinyl benzene copolymers 537-539114-117 gpjj acrylic ester/divinyl benzene copolymers 540, respectively." These materials are involved in the reaction as substrate (539)" or, more frequently, as amine reagent (sec also Fig. 163, Chap. Ill) when the crosslinked product, containing amino groups, is allowed to react with phosphorous acids (537,538, and 540). Thus, chelating properties are assumed by the resins. 

Other o-nitrophenol-containing resins have been prepared with the aim of increasing the distance between the reactive center and the macromolecular backbone, which should accelerate the active ester formation by achieving an easier approach of the reagents. Thus, the Friedel-Crafts alkylation of styrene-divinyl-benzene copolymer with 4-hydroxy-3-nitrobenzyl chloride promoted by aluminium trichloride gave 4-hydroxy-3-nitrobenzylated polystyrene (70) (approximately 30% of the aromatic rings of the polymer were substituted according to elemental... 

The seed latexes used as the cores of the imprinted particles were prepared from hydrophilic or hydrophobic polymers. The hydrophilic seeds were prepared from methyl methacrylate and methyl methacrylate/ethyleneglycol dimethacrylate copolymers, while the hydrophobic seeds were composed of polystyrene or styre-ne/divinyl benzene copolymers. Hydrophilic- and hydrophobic-imprinted shells were then laid over these cores. It was found that the best cholesterol recognition was obtained with a hydrophilic-imprinted shell and a poly(methyl methacrylate) core. However, the performance deteriorated when the core was lightly cross-linked with ethyleneglycol dimethacrylate. In a second paper [10], imprinted polymers were prepared by the noncovalent approach with cholesterol rebinding relying upon hydrophobic interactions between cholesterol and the imprinted shell. To achieve this, the template was modified to give it the characteristics of a surfactant. The structure of the template surfactant is illustrated in Fig. 2. 

Reverse Phase Chromatography. Microparticulate silica columns, and, more recently, more stable polymer matrices (e.g. vinyl alcohol copolymer gels (50) and polystyrene divinyl benzene resins) are modified with relatively nonpolar hydrocarbon chains (usually Cj g) to produce reverse phase (RP) columns. 

The sulfonation of polystyrene and styrene divinyl benzene copolymers has been extensively studied as their products are ion exchangers for the recovery of metals and have many other uses. " Some of the sulfonalkylation reactions of polystyrene have been summarized by Cameron (see Scheme 26). 

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]. 

Polystyrene resin, frequently used resin material for solid-phase peptide synthesis (SPPS). The polymeric support for SPPS must be chemically inert, mechanically stable, completely insoluble in the solvents used, and easily separated by filtration. For many applications a copolymer of polystyrene with 1% of divinyl benzene as crosslinker is used. The dry resin beads are able to swell up to the five-or sixfold volume in the different organic solvents mainly used for peptide synthesis (e.g., dichloromethane or dimethylfor-mamide). For SPPS the resin material must be chemically functionalized in order to allow for attachment of a handle/liker (e.g. Wang resin), or the first amino acid (—> Merrifield resin). Hydrophilic tentacle polymers gels (TentaGel) are obtained by grafting polyethylene glycol (PEG) chains with an arbitrary degree of polymerization onto porous polystyrene beads. 

It will be recalled that immobilized PT catalysts have not found favor with the industry because of the diffusional resistance of the solid that leads to reduced reaction rates. However, if an immobilized version of a soluble catalyst can be prepared that at least matches the performance of the soluble catalyst, it should be favored because of its other advantages. Quaternary ammonium salts are the most commonly used catalysts along with copolymers of polystyrene cross-linked to divinyl benzene as the solid supports. Use of PEG as a support has also been reported (MacKenzie and Sherrington, 1980 Kimura and Regen, 1983 Hradil and Svec, 1984). 

Sulfonation reactions of polystyrene and its copolymers with divinyl benzene are carried out commercially to prepare ion exchange resins. Partial sulfonations of polystyrenes are achieved in the presence of ethers. When more than 50% of the aromatic rings are sulfonated, the polymers become water soluble. At lesser amounts of sulfonation (25-50%), the polymers are solvent soluble. ... 

Crosslinked polystyrene (copolymer with divinyl benzene) is now a favorite support material. Perhaps the main reason for choosing crosslinked polystyrene is that it can be functionalized in many ways. It can be nitrated, chloromethylated, sulfonated, lithiated, carboxylated, and acylated. The greatest use has been made of the chloromethylated and lithiated derivatives. This is because these two derivatives can react with nucleophilic and electrophilic reagents, respectively, resulting in a wide range of functionalized polymers. See Section 8.4.3 for an illustration. 

Nakagawa and co-workers [18] used techniques based on high resolution Py-GC and Py-GC and TGA to measure thermal degradation of chloromethyl substituted polystyrene. A typical TGA weight loss curve is shown in Figure 4.1. Degradation starts at 200 "C and peaks at 400 °C. Typical pyrolysis products of chloromethylated styrene-divinyl benzene (St-DVB) copolymers are the monomers, dimers and trimers of styrene, p-methyl styrene, and divinyl and ethyl styrene. For styrene chloromethyl St-DVB copolymers, in addition to the above, /-methyl styrene monomer and m- and p-chloromethyl styrene monomers are also present in pyrolysates. 

Many different support materials were developed [3, 4] since the original use by Merrifield of a polystyrene-based support material for polypeptide synthesis [5]. The work of Merrifield is described in Chap. 8 (see section on proteins). Beads of copolymers of styrene with divinyl benzene are available commercially and have been widely used as supports for many reactions. Many other polymeric materials are also used. These can be various other type of copolymers of styrene or with other polymers. The list includes cellulose, starch, polyalkanes, polyamides, poly(glycidyl methacrylate), polyisobutylene, polynorbomene, polyacrylamide, and others. In some instances, even glass was used. The more prominent support materials are presented below. 

Cross-linked polystyrene (copolymer with divinyl benzene) was the original support material used by Merrifield for polypeptide syntheses. The material is actually a terpolymer of styrene, chloromethyl styrene, and divinyl benzene. 

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