Macroporous polymer beads suspension polymerization using

The syndiesis of macroporous polymer beads by suspension polymerization using scCOa as a pressure-adjustable porogen. 

Washington, D.C., 2001, p.125-6. 012 SYNTHESIS OF MACROPOROUS POLYMER BEADS BY SUSPENSION POLYMERIZATION USING SUPERCRITICAL CARBON DIOXIDE AS A PRESSURE-ADJUSTABLE POROGEN Wood C D Cooper AI Liverpool,University... 

Regularly macroporous ionexchange resins are prepared by suspension polymerization using water as supporting fluid. In addition to the monomer mixture a pore forming agent is included in the suspended droplets. Polymerization occurs Inside the droplets. At the end of the polymerization reaction the resin beads are removed from the water and sulfonated to creat acid groups on the polymer surface. 

The most common supports are insoluble particles of polystyrenes (PS), cross-linked with divinylbenzene (DVB), and silica gel (SG). Soluble polymers have been used as supports and separated by precipitation or by ultrafiltration. Insoluble PS beads are prepared by suspension polymerization. They can be either microporous or macroporous (synonymous with macroretic-ular). " Typical average particle diameters are 50 gm for peptide synthesis and 500 jum for ion exchange. PS beads are used in the form of solvent-swollen gels. The micropores are created by solvent, and removal of solvent collapses the pores. A macroporous polymer retains pores in the dry state and may have as much as 700 m g" of internal surface. The macropores are created during polymerization by a solvent from which the polymer precipitates as it is formed. A macroporous polymer is usually, but not necessarily, highly cross-linked. In a good solvent, the polymer phase of a macroporous PS also becomes a microporous, solvent-swollen gel. 

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