Styrene/divinylbenzene

After cross-linking to give well defined pores, styrene-divinylbenzene represents the most important stationary phase for size-exclusion chromatography. 

Cross-linked polystyrene is a versatile stationary phase resulting from copolymerization of styrene and divinylbenzene (Fig. 7.11). The amount of 

Example of a stationary phase with polar embedded group , different selectivity for polar analytes than the classical alkyl phases, for eluents with high water content. 

Styrene-divinylbenzene phases may be just microporous or contain a mixture of micro- and macropores (Fig. 7.12). The presence of macropores with a diameter of several lOnm facilitates access of larger molecules to the active sites. 

In contrast to silica, styrene-divinylbenzene is stable in the pH range 1-13, Styrene-divinylbenzene can be used as a reversed-phase material in 

Ion exchangers are obtained by incorporating suitable groups into the matrix, as shown in Fig. 7.14. In a similar manner, it is possible to insert C18H37 groups this type of octadecyl phase does not contain any unreacted OH groups as with reversed phases based on silica. 

Nagagawa and co-workers [32] investigated the thermal degradation behaviour of anionically and radically polymerised styrene divinylbenzene (DVB) copolymer. 

Factor analysis has been used for extracting information from mass spectra recorded in a TG-MS analysis of the styrene-isoprene mixture. Statheropoulos and co-workers 

The first decomposition step of Kraton 1107 seems to consist of four overlapped decomposition steps. In the first step, 1 -methyl-4-( 1 -methylethenyl)-cyclohexene and 1,4-dimethyl-4-ethenyl-cyclohexene start to evolve. In the second step, the evolution of isoprene monomer is taking place. In the third step, a mixture of alkyl-benzene, cycloalcadienes, cycloalkenes and saturated polycyclic hydrocarbons evolves whilst 

Retention time (min) Substance Eight most abundant masses (relative intensities) 

Reproduced with permission from M. Statheropoulos, K. Mikedi, N. Tzamtzis and A. Pappa, Analytica Chimica Acta, 2002, 461, 215. 2002, Elsevier [33]  

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This type of analysis requires several chromatographic columns and detectors. Hydrocarbons are measured with the aid of a flame ionization detector FID, while the other gases are analyzed using a katharometer. A large number of combinations of columns is possible considering the commutations between columns and, potentially, backflushing of the carrier gas. As an example, the hydrocarbons can be separated by a column packed with silicone or alumina while O2, N2 and CO will require a molecular sieve column. H2S is a special case because this gas is fixed irreversibly on a number of chromatographic supports. Its separation can be achieved on certain kinds of supports such as Porapak which are styrene-divinylbenzene copolymers. This type of phase is also used to analyze CO2 and water. 

To illustrate the specific operations involved, the scheme below shows the first steps and the final detachment reaction of a peptide synthesis starting from the carboxyl terminal. N-Boc-glycine is attached to chloromethylated styrene-divinylbenzene copolymer resin. This polymer swells in organic solvents but is completely insoluble. ) Treatment with HCl in acetic acid removes the fert-butoxycarbonyl (Boc) group as isobutene and carbon dioxide. The resulting amine hydrochloride is neutralized with triethylamine in DMF. 

Structures of styrene, divinylbenzene, and a styrene-divinylbenzene co-polymer modified for use as an ion-exchange resin. The ion-exchange sites, indicated by R, are mostly in the para position and are not necessarily bound to all styrene units. 

Polypeptide Synthesis and Analysis. Sihca or controUed-pore glass supports treated with (chloromethyl)phenylethyltrimethoxysilane [68128-25-6] or its derivatives are replacing chloromethylated styrene—divinylbenzene (Merrifield resin) as supports in polypeptide synthesis. The sdylated support reacts with the triethyl ammonium salt of a protected amino acid. Once the initial amino acid residue has been coupled to the support, a variety of peptide synthesis methods can be used (34). At the completion of synthesis, the anchored peptide is separated from the support with hydrogen bromide in acetic acid (see Protein engineering Proteins). 

Other developments in chelating resins include fibers made from poly(ethylene glycol) and poly(vinyl alcohol) to which EDA was attached with epichl orohydrin (281) and a styrene—divinylbenzene resin with pendant EDTA or DETPA groups (282). 

The first, and still widely used, polymer-supported ester is formed from an amino acid and a chloromethylated copolymer of styrene-divinylbenzene. Originally it was cleaved by basic hydrolysis (2 N NaOH, FtOH, 25°, 1 h). Subsequently, it has been cleaved by hydrogenolysis (H2/Pd-C, DMF, 40°, 60 psi, 24 h, 71% yield), and by HF, which concurrently removes many amine protective groups. Monoesterification of a symmetrical dicarboxylic acid chloride can be effected by reaction with a hydroxymethyl copolymer of styrene-divinylbenzene to give an ester a mono salt of a diacid was converted into a dibenzyl polymer. ... 

Hays measured the current associated with electrically charged 99 p.m diameter particles of styrene divinylbenzene particles as these particles traversed gaps of 520 and 137 p.m separating two parallel electrodes. Based on these results. Hays [81 ] argued for the existence of locally charged patches on the particles. 

Modern SEC columns are packed with material other than polystyrene gels, such as porous silica particles or highly cross-linked styrene-divinylbenzene copolymers. Because of improvements in speed and resolution, the term SEC is sometimes replaced by the term high-performance size-exclusion chromatography (HPSEC). 

TSK-GEL H type columns are for gel-permeation chromatography (GPC) in organic solvents. They are packed with porous poly(styrene-divinylbenzene) resins that have a high degree of cross-linking. 

It is well known that anionic samples tend to adsorb on poly(styrene-divinylbenzene) resins. However, cationic samples tend to be repelled from the resins. The mechanism seems to be an ionic interaction, although the poly(styrene-divinylbenzene) resin should be neutral. The reason is not well clarified. Therefore, it is recommended to add some salt in the elution solvent when adsorption or repulsion is observed in the analyses of polar samples. For example, polysulfone can be analyzed successfully using dimethylformamide containing 10 mM lithium bromide as an elution solvent, as shown in Fig. 4.42. 

Styrene—divinylbenzene copolymer Polyhydroxymethaerylate Polyvinyl alcohol Polyhydroxylated silica... 

Shodex has a wide variety of columns for organic GPC using organic solvents. The columns are packed with porous styrene-divinylbenzene copolymer gels especially developed for GPC use. Five types of standard-size GPC columns packed with different solvents are available. Downsized GPC columns are also available. 

The Shodex GPC KF-600 series is packed with 3- im styrene-divinylbenzene copolymer gels in a column having a volume of about one-third compared to standard-types of columns, which are best suited for reducing the organie solvents eonsumption, shortening the analysis time, and lowering the detection limit (Table 6.5). 

PSS columns for organic eluents PSS SDV columns are based on proven styrene-divinylbenzene type sorbents with improved sorbent characteristics and column technology. 

For the classical form of size exclusion chromatography in organic solvents, packings based on highly cross-linked styrene-divinylbenzene are used. For SEC of polar polymers using polar or aqueous solvents, packings based on a polar methacrylate polymer are used. Diol-derivatized silica is used for the separation of proteins and other polar polymers. The different packings will be discussed in sections dedicated to their different application areas. 

The Styragel family of packings represents the classical packing of size exclusion chromatography (2). It is based on cross-linked styrene-divinylbenzene particles. Pore sizes range from around 20 A for the Styragel... 

The styrene-divinylbenzene matrix of the Styragel packings is chemically very inert, which makes this family of packings useful for a broad range of applications. The chromatographic conditions for the analysis of many polymers have been worked out in detail. A more specific discussion of the solvents recommended for the different polymer types is included in Section III,A,4. 

Unlike earlier sulfonated styrene/divinylbenzene copolymers, these sulfonated gels can he run in virtually any solvent from water and buffers to pure organics as well as most any mixed solvent systems desired. In aqueous systems they absorb water and in organic solvents they stay swollen by imbibing organic solvents. 

The plate number for the same column also depends on the eluent, e.g., a permitted operation for some styrene-divinylbenzene columns is to change the eluent from tetrahydrofuran (THF) to dimethylacetamide (DMAC) and then return to THF. The plate number in DMAC is considerably lower than in THF. After the replacement of DMAC by THF the old N value is obtained again. 

There are different reasons to discard a column a column can be damaged by irreversible adsorption of reactive polymer samples. Small amounts of styrene oligomers are known to permanently elute from styrene-divinylbenzene materials with tetrahydrofuran as the eluent, which means a continuous shear degradation of the separation material and consequently a decrease of the packing quality this observation is very important if fractions are collected and used for further analyses, e.g., for the determination of infrared (IR) spectra. One can presume that similar effects are present with other organic materials too. 

Monoesterification of a symmetrical dicarboxylic acid chloride can be effected by reaction with a hydroxymethyl copolymer of styrene-divinylbenzene to give an ester a mono salt of a diacid was converted into a dibenzyl polymer." ... 

These small columns,(usually 10 mm X 1-4.6 mm i.d.) are normally packed with 10-40 p.m sorbents such as Cig-bonded silica, Cg-bonded silica or styrene-divinylbenzene copolymer. These sorbents are not very selective and more selective sorbents, such as the immunosorbent (94), have also been used with good results. Coupling of SPE-gas chromatography is in fact the one most often used in environmental analysis because it reaches a high level of trace enrichment, eliminates water and elutes retained compounds easily with an organic solvent that can be injected into the gas chromatograph. 

C. Aguilar, P. BottuII and R. M. Marce, On-line and off-line solid-phase extraction with styrene-divinylbenzene-membrane extr action disks for determining pesticides in... 

Sheu and coworkers [111] produced polysty-rene-polydivinylbenzene latex interpenetrating polymer networks by the seeded emulsion polymerization of styrene-divinylbenzene in the crosslinked uniform polystyrene particles. In this study, a series of uniform polystyrene latexes with different sizes between 0.6 and 8.1... 

Figure 20 A typical scanning electron micrograph of the macroporous uniform poly(styrene-divinylbenzene) late> particles. Magnification 1200 x, (particle size = 16.0/rm average pore diameter = 200 nm).

A research group in Lehigh University has extensively studied the synthesis and characterization of uniform macroporous styrene-divinylbenzene copolymer particles [125,126]. In their studies, uniform porous polymer particles were prepared via seeded emulsion polymerization in which linear polymer (polystyrene seed) or a mixture of linear polymer and solvent were used as inert diluents [125]. The average pore diameter was on the order of 1000 A with pore volumes up to... 

The starting material for the synthesis of this chelating resin is chloromethylated styrene-divinylbenzene, which undergoes an amination reaction and is then treated with monochloracetic acid ... 

The materials originally used as stationary phases for GPC were the xerogels of the polyacrylamide (Bio-Gel) and cross-linked dextran (Sephadex) type. However, these semi-rigid gels are unable to withstand the high pressures used in HPLC, and modern stationary phases consist of microparticles of styrene-divinylbenzene copolymers (Ultrastyragel, manufactured by Waters Associates), silica, or porous glass. 

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