POROUS POLYHEMA BEADS PREPARED BY SUSPENSION POLYMERIZATION IN AQUEOUS-MEDIUM

A study was made of the effect of the type of low-molecular-weight porogen on the properties of polyHEMA beads (sphericity, bead size, porosity, and morphology), prepared by radical suspension copolymerization of 2-hydroxyethyl methacrylate (HEMA) with ethylene dimethacrylate (EDMA) in aqueous dispersion. The porogen used was cyclohexanol, mixed with various alcohols, hydrocarbons, butyl acetate, or cyclohexanone. Spherical particles, with a size of hundreds of mum and a porosity of up to 68%, can be prepared using a mixture of cyclohexanol and 1-octanol in a volume ratio of 3 : 2. The tendency for the particles to agglomerate, observed in the presence of benzyl alcohol, 1-butanol, or cyclohexanone, can be a consequence of a change in the polymerization mechanism connected with the excessive solubility of these porogens, and thus also the initiator in water. (C) 1993 John Wiley & Sons, Inc.