Abstract: A transparent polyurethane-hydrogel composition includes a reaction product in aqueous solvent of a prepolymer and a water-soluble crosslinker in the substantial absence of organic solvent, and such a composition can be prepared by admixing a prepolymer and a water-soluble crosslinker in aqueous solvent and in the substantial absence of organic solvent. A prepolymer is present in an amount of no greater than about 5 weight percent based on total weight of all hydrogel components. The prepolymer is generally prepared from at least one water-soluble polyol and an isocyanate. A water-soluble crosslinker generally has a crosslinker functionality of at least 2 and is selected to provide a site ratio of initial isocyanate to crosslinker (i.e., moles NCO×functionality/moles crosslinker×functionality) of at least about 1.5 and no greater than about 2.6. In one embodiment, a crosslinker is effective to react with and solubilize residual isocyanate concurrently with the reaction between prepolymer and crosslinker.

Abstract: A transparent polyurethane-hydrogel composition includes a reaction product in aqueous solvent of a prepolymer and a water-soluble crosslinker in the substantial absence of organic solvent, and such a composition can be prepared by admixing a prepolymer and a water-soluble crosslinker in aqueous solvent and in the substantial absence of organic solvent. A prepolymer is present in an amount of no greater than about 5 weight percent based on total weight of all hydrogel components. The prepolymer is generally prepared from at least one water-soluble polyol and an isocyanate. A water-soluble crosslinker generally has a crosslinker functionality of at least 2 and is selected to provide a site ratio of initial isocyanate to crosslinker (i.e., moles NCO×functionality/moles crosslinker×functionality) of at least about 1.5 and no greater than about 2.6.