Preparation and morphology study of microporous poly(HEMA–MMA) particles

Porous poly(2‐hydroxyethyl methacrylate‐methyl methacrylate) particles crosslinked with ethylene glycol dimethacrylate were synthesized by free‐radical suspension copolymerization in an aqueous phase initiated by an oil‐soluble initiator, 2,2‐azobisisobutyronitrile. 1‐octanol was used as a pore forming agent (porogen). The porous structures, the particle morphology, and the swelling capacity of the resultant polymer in water at room temperature were studied at different crosslink densities and under various porogen concentrations. The analysis via Scanning Electronic Microscopy (SEM) indicated that permanent pores remained in the dried polymeric particles prepared in the presence of the porogen at certain crosslink densities. According to the studies via the SEM pictures and the pore size distributions, higher porogen concentration promotes the formation of more pores, and higher crosslink density results in narrower pore size distribution. The swelling capacity of the particles in water at room temperature decreases with an increase in the crosslink density, and the existence of the highly porous structures enhances the swelling capacity of the porous particles of poly(2‐hydroxyethyl methacrylate‐methyl methacrylate). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 707–715, 2007