Porous poly(2-hydroxyethyl acrylate) hydrogels

Porous hydrogels were prepared by copolymerisation of 2-hydroxyethyl acrylate and ethyleneglycol dimethacrylate (as crosslinking agent) in solution using water or ethanol as solvents. Macroscopic pores are formed due to the segregation of the solvent from the polymer network during the polymerisation 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 swollen in water the pores opened and the volume fraction of pores could be determined by weighing. The pore morphology was observed by scanning electron microscopy. The dependence of the pore size on the solvent used and on the 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 α) dynamic-mechanical relaxation process. These spectra were correlated with the morphology of the samples.