Most of the macroporous polymers are almost exclusively produced in a shape of spherical beads that are used as ion-exchange resins, chromatographic separation media, adsorbents, etc. These polymers are characterized by their rigid porous matrix that persists even in the dry state. Typically, macroporous beads are produced by a suspension polymerization process using a polymerization mixture that contains a crosslinking monomer, monovinyl monomer and an inert diluent, the porogen. Porogens can be solvating or non-solvating solvents for the polymer that is formed, or soluble non-crosslinked polymers or mixtures of polymers and solvents. The mechanism of pore formation as well as the properties of macroporous polymers and their applications have been reviewed several times. However, all studies of the mechanism of formation of macroporous structures have focused exclusively on materials prepared by suspension polymerization.
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