HYDROPHILIC SPONGES BASED ON 2-HYDROXYETHYL METHACRYLATE .1. EFFECT OF MONOMER MIXTURE COMPOSITION ON THE PORE-SIZE

A large number of hydrophilic sponges were prepared by polymerisation of 2-hydroxyethyl methacrylate in variable concentrations of water (60-90% wt) in the initial monomer mixture. Concentration and type of crosslinking agents (ethylene dimethacrylate (EDMA) and hexamethylene dimethacrylate (HDMA)) and concentration of redox initiators were also changed. All sponges were examined in cross-section by conventional and environmental scanning electron microscopy. Micrographs indicated that, in order to obtain sponges with characteristics appropriate for biomedical use (e.g. pores larger than 10mum), the minimum water concentration was 75% wt with EDMA as a crosslinking agent, or 70% wt with HDMA, for contents of crosslinking agents and initiator less than 1% wt. Micrographs also showed that higher contents of crosslinking agents or initiator led to larger pores. In high concentrations of water, this effect was less evident. Microscopic details confirmed the crucial role of the phase separation during polymerisation.