The preparation of poly(2-hydroxyethyl methacrylate) and poly {(2-hydroxyethyl methacrylate)-co-[poly(ethylene glycol) methyl ether methacrylate]} by photoinitiated polymerisation-induced phase separation in water

This paper describes the application of a photoinitiated polymerisation-induced phase separation method to the preparation of PHEMA and P[HEMA-co-(MeO-PEGMA)] hydrogels. PHEMA sponges having a morphology of agglomerated polymer droplets and interconnected pores were easily prepared from aqueous mixtures containing HEMA, EDGMA (crosslinker) and DPAP (photoinitiator). P[HEMA-co-(MeO-PEGMA)] copolymers having similar morphologies could also be prepared, provided that the proportion of MeO-PEGMA in the copolymer was relatively small. When higher proportions of MeO-PEGMA were used, the resulting polymers were gels rather than sponges, and did not show the sought after droplet/pore morphology. P[HEMA-co-(MeO-PEGMA)] copolymers having higher proportions of MeO-PEGMA and having a morphology of agglomerated polymer droplets and interconnected pores were easily prepared by addition of NaCl to the polymerisation mixture. Thus, incorporation of MeO-PEGMA and addition of NaCl to the photopolymerisation mixtures provides an easy way of tuning the hydrophilicity of PHEMA copolymer sponges without compromising the desired porous morphology. (C) 2009 Elsevier Ltd. All rights reserved.