HYDROPHILIC SPONGES BASED ON 2-HYDROXYETHYL METHACRYLATE .5. EFFECT OF CROSS-LINKING AGENT REACTIVITY ON MECHANICAL-PROPERTIES

Tensile properties of poly(2-hydroxyethylmethacrylate) (PHEMA) sponges crosslinked with divinyl glycol (DVG) and ethylene glycol dimethacryl ate (EDMA), two crosslinking agents having very different hydrophilici ty and reactivity, were compared. Crosslinking agent concentrations we re varied from 0.5 to 5.0mol%, at a fixed water content of 80wt% in th e monomer mixture. The poorer tensile properties of EDMA-crosslinked s ponges were attributed to network inhomogeneities, which were presumed to arise from the formation of: rigid crosslinks within the phase-sep arated droplets. Comparison of the crosslinking efficiencies of DVG an d EDMA via stress (compression)-strain measurements was not possible b ecause of the non-linear response of the sponges to compressive strain s.