The invention provides a hydrogel composition comprising water and a
hydrophilic polymer, wherein the hydrogel composition has (a) an ultimate
tensile strength of about 10 kPa or more, (b) a compressive strength of
about 70 kPa or more, or (c) an ultimate tensile strength of about 10 kPa
or more and a compressive strength of about 70 kPa or more. The invention
further provides methods for producing a hydrogel composition.