Production of poly[(ethylene glycol dimethacrylate)-co-acrylamide] based hydrogel beads by suspension copolymerization

Poly(EGDMA/AAm) copolymer beads, in the size range of 25-170 mu m, were produced by suspension copolymerizations of the respective monomers, i.e., ethylene glycol dimethacrylate (EGDMA) and acrylamide (AAm), in aqueous media, with or without using toluene as the diluent. Poly(vinyl alcohol) and benzoyl peroxide were used as the stabilizer and the initiator. The beads were characterized by optical microscopy, FTIR-DRS, and elemental analysis. Swellabilities in aqueous media were obtained. Dry state porosities were calculated from densities measured pycnometrically. In the polymerization without toluene, nonswellable and nonporous microbeads were obtained, with AAm incorporation up to 9.55%. Including toluene in the polymerization recipe resulted in larger, swellable (with swelling ratios of 10-16%) and microporous (with dry state porosities of 0.020-0.080) beads with higher AAm incorporations (up to 29.9%) and high polymerization yields up to 96%.