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Porous monolithic materials with high surface areas have been prepared from commercial 80% divinylbenzene. The pore properties of these materials are controlled by the type and composition of the porogenic solvent and by the percentage of cross-linking monomer (divinylbenzene) in the polymerization mixture. Surface area was found to increase with the divinylbenzene content of the monolith. Using high-grade divinylbenzene and a suitable porogenic solvent, monolithic materials with specific surface areas as high as 400 m 2 /g yet still permeable to liquids at reasonable back pressure were obtained for the first time. A macroporous material with hydrodynamic properties optimized for solid-phase extraction has been designed and its permeability and adsorption ability was demonstrated by adsorbing phenols at flow velocities that exceed those of current materials by a factor of 30. A unique set of polymerization conditions had to be developed to allow the incorporation of polar 2-hydroxylethyl methacrylate into the hydrophobic nonpolar backbone of the divinylbenzene monolithic material. This improves wettability while high-flow properties are maintained and unusually high recoveries of polar compounds are allowed.

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Porous polymer monoliths are a new category of materials developed during the last decade. These materials are prepared using a simple molding process carried out within the confines of a closed mold. Polymerization of a mixture that typically contains monomers, free-radical initiator, and porogenic solvent affords macroporous materials with large through-pores that enable flow-through applications. The versatility of the preparation technique is demonstrated by its use with hydrophobic, hydrophilic, ionizable, and zwitterionic monomers. The porous properties of the monolith can be controlled over a broad range. These, in turn, determine the hydrodynamic properties of the devices that contain the molded media. Since all the mobile phase must flow through the monolith, the mass transport within the molded material is dominated very much by convection, and the monolithic devices perform well even at very high flow rates. The applications of monolithic materials are demonstrated on the chromatographic separation of biological compounds and synthetic polymers, electrochromatography, gas chromatography, enzyme immobilization, molecular recognition, and in advanced detection systems. Grafting of the pore walls with selected polymers leads to materials with completely changed surface chemistries.