Macroporous copolymers of glycidylmethacrylate (GMA) with ethyleneglycol dimethacrylate were prepared using polystyrene as a porogen in toluene solution. The use of the polystyrene as porogen improves the porous properties of the macroporous polymers. The effects of the polymeric porogen and of the temperature of polymerization on the shape and size of the particles, porous structure and density of epoxide groups have been studied. By working at 55degreesC instead 70degreesC, it was possible to obtain a polymer that possesses a specific surface of 20 m(2)/g, that corresponds to a surface seven times lower than that of a reference polymer (142 m(2)/g) obtained via the normal procedure using cyclohexanol-dodecanol mixture as porogenic and solvent compounds. The increase of the porosity of the GMA beads of good spherical shape and small size (35% of 10 mum particles) allowed a smaller resistance against the flow of the eluent. This greater porosity is accompanied by a better functional density of epoxide groups (197 mumol/m(2)) vs. original polymer (29 mumol/m(2)). (C) 2003 Elsevier B.V. All rights reserved.