Novel hydrophilic cyclic monomers in hydrogel synthesis

A range of hydrogels was prepared by the copolymerisation of 2-hydroxyethyl methacrylate (HEMA) with various hydrophilic cyclic monomers (CM) derived from cis-1,2-dihydroxy-3,5-cyclohexadiene (DHCD). The specific systems investigated were the cis-1,2-bis(2,3-epoxybutanoyloxy)-, cis-1,2-bis(10,11-epoxyundecanoyloxy)-, cis-1,2-bis(trimethylsiloxy)- and cis-1,2-bis(tert-butyldimethylsiloxy)-3,5-cyclohexadienes. The EWC, tensile strength and initial modulus of the poly HEMA-CM hydrogels derived from the epoxy compounds showed lower EWCs but similar mechanical properties compared with polyHEMA itself. Treatment of the hydrogel derived from cis-1,2-bis(2,3-epoxybutanoyloxy)-3,5-cyclohexadiene with 20% sodium hydroxide increased the EWC value markedly but produced highly fragile materials.