Preparation of macroporous poly(2-hydroxyethyl methacrylate) hydrogels by enhanced phase separation

Macroporous poly(2-hydroxyethyl methacrylate) (p(HEMA)) hydrogels were prep ared in the presence of a 0.3-0.7 M NaCl solution. The pore morphology of t he p(HEMA) hydrogels was dependent on the concentration of NaCl for a const ant monomer solution to aqueous solution ratio. Swelling studies showed an increase in equilibrium water content and hydrogel porosity as the NaCl con centration in the polymerization medium increased from 0 to 0.7 M. The equi librium water content, however, decreased as the NaCl concentration in the swelling medium increased. The frozen water content increased and non-froze n water decreased with an increase in the NaCl concentration in the polymer ization medium. Mechanical testing indicated that the elastic modulus of th e hydrogels was not affected by the increased porosity until the pores beca me interconnected. These data suggest that the addition of NaCl to the poly merization medium results in a multi-phase separation during fabrication th at produces macroporous hydrogels of controlled morphology. (C) 2000 Elsevi er Science Ltd. All rights reserved.