Copolymers of styrene and divinylbenzene

Hydrophobic sorbents including octadecyl, octyl, diphenyl, cyclohexyl, phenyl, butyl, ethyl, methyl, and copolymers of styrene and divinylbenzene can be applied for retaining nonpolar to medium polar analytes. In this list, the styr-ene-divinylbenzene copolymer phases such as PRP-1 and XAD-2 are the most nonpolar phases, while the methyl phase is the least nonpolar one. The analytes are adsorbed onto the hydrophobic materials by means of van der Waals interactions and, to some extent, by hydrophobic bonding or dipole-dipole interactions. 

Membranes may be manufactured by mixing powdered ion exchange resin with a solution of binder polymer and pouring the heated mixture under pressure onto a plastic mesh or cloth. The concentration of the ion exchanger is normally 50-70%. They are chiefly copolymers of styrene and divinylbenzene, sulfonated with sulfuric acid for introduction of the cation exchange group. 

Strong Base Anion Exchangers. As in the synthesis of weak base anion exchangers, strong base resins are manufactured from styrenic as well as acrylic copolymers. Those based on copolymers of styrene and divinylbenzene are chloromethylated and then aminated. These reactions are the same as for the styrenic weakbase resins. The essential difference is the amine used for amination. Trimethylamine [75-50-3], N(CH3)3, and A/,A/-dimethylethanolamine [108-01-0], (CH3)2NCH2CH2OH, are most commonly used. Both form quaternary ammonium functional groups similar to (8). 

Currently, the most widely used adsorbents in RPC are silica resins, containing a hydrophobic phase, usually octyl (C8), octyldecyl (C18), methyl (Cl), or phenyl groups. Additionally, new adsorbents based on organic materials such as methacrylate, polystyrene, and copolymers of styrene and divinylbenzene have been developed (Hearn, 1998). 

The growing popularity of reversed phase chromatography in particular has prompted polymer manufacturers to investigate the use of polymeric media for this mode of operation. Macroporous copolymers of styrene and divinylbenzene have similar properties to silica based stationary phases bonded with alkyl chains. However, the absence of leachables and stability at high pH can offer advantages under certain circumstances. High quality, mechanically stable macroporous polymeries are now manufactured at much larger scales than the... 

From data on copolymers of styrene and divinylbenzene (Bicerano et al. 1996) we constructed a plot of Tg vs. 1/Mcri in order to determine the constant Kcr. Results are shown in Fig. 6.5 and it follows a value of 5.2 x 104 K mol g 1 for Kcri. Of course, the value of term Kcri depends on the system of consideration. 

Ion-exchange separations can also be made by the use of a polymer with exchangeable anions in tliis case, the lanthanide or actinide elements must be initially present as complex ions (11,12). The anion-exchange resins Dowex-1 (a copolymer of styrene and divinylbenzene with quaternary ammonium groups) and Ambedite IRA-400 (a quaternary ammonium polystyrene) have been used successfully. The order of elution is often the reverse of that from cationic-exchange resins. 

Crosslinking affects mainly the a relaxation of polystyrene. Crosslink formation inhibits the molecular motion and, therefore, always causes a net increase in Ta. For example, Ishii et al. [34], working on a copolymer of styrene and 4-ethylstyrene (8mol%), found a shift of 34 K (1Hz) in Ta towards high temperature. The crosslinked polystyrenes of major commercial interest are copolymers of styrene and divinylbenzene. Results of a systematic study of this system have shown that Tg could be represented by the equation [35]... 

Highly hydrophobic sorbents including porous carbon and copolymers of styrene and divinylbenzene (SDB) were widely investigated for environmental applications. The particle-loaded membranes containing modified SDB particles with surface sulfonic acid groups were successfully used for recovering different alcohols, phenols, aldehydes, ketones, or esters from aqueous samples [221]. Carbon-based PLM were also used for isolation of highly polar pesticides from water [222]. 

Porous polymers also are useful for gas analyses and for very polar molecules, such as amines, glycols, and acids. Copolymers of styrene and divinylbenzene and others, such as ethylvinylbenzene-divinylbenzene, cross-linked acrylic ester, vinylpyridine, pyrollidone, and ethylene glycol dimethacrylate, are commercially available. ... 

The synthesis of cross-linked copolymers of styrene and divinylbenzene has been studied intensively and is well documented. The starting monomer is styrene, and divinylbenzene (DVB) is used as cross-linker. The amount of DVB can reach up to 55 wt.%. At 55% DVB, the copolymer shows practically no swelling and possesses a permanent porosity. Figure 3.21 illustrates the network structure of poly(styrenedivi-nylbenzene) (St-DVB). 

The ion-exchange resin is composed of a polymeric skeletal structure (e.g., copolymer of styrene and divinylbenzene), onto which ionic groups (e.g., —S03 ) are attached. The charges of the ionic groups are neutralized by counter ions, which can move freely within the polymer skeleton (e.g., H ). Figure 2.38 shows schematically the structure of an ion-exchange resin. In applications such as acid catalysts, they are typically used as sulfonated copolymer of styrene and divinylbenzene. The maximum temperature of operation is 120-150 °C, and pore volume and pore size distribution depend on the polarity of the reaction mixture. 

PCD is a copolymer of styrene and divinylbenzene where all the styrene groups are chloromethylated. When the content of divinylbenzene was 2 mol%, the chloromethyl groups were found to remain almost intact during suspension polym-... 

The best known stationary phases are issued from copolymers of styrene and divinylbenzene, in order to obtain packings hard enough to resist pressure in the column. They are made of spherical particles with diameters of 5 to 15)u,m (Figure 4.4) that are modified on the surface in order to introduce functional groups with acidic or basic properties. 

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