Hydrophilic Sponges Based on 2-Hydroxyethyl Methacrylate. III. Effect of Incorporating a Hydrophilic Crosslinking Agent on the Equilibrium Water Content and Pore Structure

The effect of using a hydrophilic crosslinking agent (divinyl glycol, DVG) on 2-hydroxyethyl methacrylate (HEMA) sponge swelling and pore morphology was evaluated. Concentrations of crosslinking agent, redox initiators and HEMA (75–90wt%) in the initial aqueous monomer mixture were varied. Anomalous sponge swelling behaviour, together with the formation of non-uniform stratified sponges was rationalised in terms of the assumed disparate free radical reactivities of DVG and HEMA. Environmental scanning electron microscopy indicated that the stratified sponges did not exhibit suitable porosity for biomedical use.