Porous poly(2-hydroxyethyl acrylate) hydrogels

Porous hydrogels were prepared by copolymerisation of 2-hydroxyethyl acryla te and ethyleneglycol dimethacrylate (as crosslinking agent) in solution us ing water or ethanol as solvents. Macroscopic pores are formed due to the s egregation of the solvent from the polymer network during the polymerisatio n process. In the dry state the polymer network had nearly the same density as the poly(2-hydroxyethyl acrylate) polymerised in bulk thus showing that the pores collapse during the drying process. When the dry samples were sw ollen in water the pores opened and the volume fraction of pores could be d etermined by weighing. The pore morphology was observed by scanning electro n microscopy. The dependence of the pore size on the solvent used and on th e monomer/solvent ratio in the polymerisation process is shown. The elastic modulus and loss tangent were measured as a function of temperature in the region of the main (or ct) dynamic-mechanical relaxation process. These sp ectra were correlated with the morphology of the samples. (C) 2001 Elsevier Science Ltd. all rights reserved.