Macroporous Styrene-Divinylbenzene Copolymers

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... 

Tatsuzawa et aq 36,37,45,59 separat.ed cold drugs and neuroleptics by using a styrene-divinyl benzene-methyl methacrylate copolymer as stationary phase. The best results were obtained with methanol - ammonia (99 1) as mobile phase. The effect of the pH and of the composition of the mobile phase on the separation were discussed. Aramaki et al.70 analyzed a series of alkaloids on a macroporous styrene-divinylbenzene copolymer with alkaline acetonitrile - water mixtures as mobile phase (Fig. 7.10). The columns showed excellent stability, and also under the strong basic conditions used for the analysis of the alkaloids. 

Column, Hitachi Gel 3010 (macroporous styrene-divinylbenzene copolymer), 10 pm (22ox4.6 mm ID), mobile phase, SI acetonitrile - water (3 7) containing 0.02 M tetrabutylammonium hydroxide, S2 acetonitrile - water (6 4) containing 0.02 M tetrabutylammonium hydroxide, S3 acetonitrile - water (6 4) containing 0.02 M ammonia, flow rate 1 ml/min, detection UV 254 nm. 

Figure 2. Fluorescence emission of solvent equilibrated macroporous styrene-divinylbenzene copolymers prepared by suspension polymerization.

A macroporous polystyrene-divinylbenzene copolymer, produced by copolymerizing a mixture of styrene and divinylbenzene, is dissolved in an organic liquid such as t-amyl alcohol or isooctane, which is a solvent for monomers. This solvent is unable to substantially swell the resulting copolymer. Macroporous cation-exchange beads are also produced from these macroporous copolymers (25,26). 

New polymeric solid supports have been devised, which include macroporous styrene-divinylbenzene containing large fixed pores, porous glass beads, insoluble carbohydrate polymers, poly(ethylene oxide), cross-linked derivatives of polyacrylamide resins, and graft copolymers of polystyrene and poly(ethylene oxide). The last two have been the most effective and widely used and have competed well with the original copoly(styrene-divi-nylbenzene) beads. 

The porogen is usually an inert solvent, or mixtures of inert solvent and polymers. The meso- and macropores in the polymer network are the voids once occupied by the porogen. Individual recipes for the preparation of macroporous polymer beads may seem complex in terms of the number of components involved and the required control of the experimental conditions. The technology, however, for their preparation has been developed to such a degree that excellent control over their properties (e.g. particle size, shape, porosity and chemistry) is routinely achieved. The vast majority of current macroporous polymers are based on styrene-divinylbenzene copolymers. Other suitable monomers include acrylates, methacrylates, hydroxyalkylacrylates, vinylpyridines and vinyl acetate. A wide range of products are available for HPLC in particle sizes from 5-20 p,m, pore diameters from about 2-400 nm, and surface areas from about 50-500 m /g [141,144,146-148]. 

Macroporous hypercrosslinked styrene-divinylbenzene copolymers and related networks... 

Polymeric adsorbents, particularly macroporous styrene—divinylbenzene (DVB) copolymers, are free from these drawbacks of activated carbons. The heat of adsorption onto the polymeric adsorbents is significandy lower and, accordingly, the regeneration of polymers proceeds under much milder conditions. As a rule, the copolymers have no functional groups (apart from those specially introduced) that are capable of catalyzing chemical transformation of an adsorbate. However, in contrast to activated carbons, the specific surface area of most polymeric adsorbents is not very high therefore, their sorption capacity is lower, often making the use of macro-porous polystyrene-type adsorbents unprofitable. This circumstance impelled scientists to develop new types of polymeric materials with an enhanced... 

Hradil et al. [395, 396] prepared a set of composite membranes containing fine particles of conventional macroporous resins or hypercrosslinked polystyrene adsorbing materials in films of poly(2,6-dimethyl-l,4-phenylene oxide) as a binder. Hypercrosslinked resins were either a commercial product, Lewatit EP63 (Bayer AG), or were obtained by crosslinking (i) a macroporous styrene—divinylbenzene (DVB) copolymer with carbon tetrachloride (Hyp-St—DVB) or (ii) a finear polystyrene with monochlorodi-methyl ether. In the latter case the reaction of bridging was conducted in a pretty diluted ethylene dichloride solution at stirring, which resulted in obtaining a particulate (1—5 pm) product. 

A styrene/divinylbenzene copolymer was phosphorylated and converted to a polymer with phenylphosphinic acid groups 41 [114] (see Experiment 5-9, Section 5.4). Ion-exchange coordination to Cu(II), Cd(II), Ni(II), Zn(II) and Eu(III) was studied. Resins with carboxylic groups in the a- and P-positions display higher metal ion uptake than those with -COOH in the y-position. Macroporous polymers 42 with a functional group based on triisobutyl-phosphine sulfide have been synthesized and characterized for the selective adsorption of Au(III) and Pd(II) [115]. 

Shea, K.J. Stoddard, G.J. Sasaki, D.Y. Flourescence probes for the evaluation of diffusion of ionic reagents through network polymers. Chemical quenching of the flourescence emission of the dansyl probe in macroporous styrene-divinylbenzene and styrene-diisopropylbenzene copolymers. Macromolecules 1989, 22, 4303-4308. 

Jacobeli H, M. Bartholin, and A. Guyot. Styrene-divinylbenzene copolymers n. Influence of the nature of the diluent on the texture of macroporous copolymers. Anghew. Makromol. Chem. 80 (1979) 31-51. 

It was in 1964 that Moore suceessfully synthesised a macroporous poly(styrene/ divinylbenzene) copolymer whieh enabled polymers to be utilised for liquid chromatography without the restrictions of operating pressure previously imposed [3]. The rigidity and controlled pore size and strueture of these polymer matrices has enabled the development of high speed, high performanee separations. 

The examined polymer-supported catalyst having two different granulations (bead size) A and B was the macroporous cross-linked copolymer of 4-vinylpyridine and 25% (4/1) divinylbenzene-styrene copolymer (commercial product named Reillex 425) [103]. Their average bead diameter (J), skeletal density (p), surface area ( Sbet). porc volume (Vp), and relative swelling ratio (SR) are given in Table 8.2. 

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