radiation - crosslinked , biodrgradable , synthetic hydrogels and their use in various applications , including certain medical applications wherein the hydrogel are implanted on or in the body of a human or animal patient . radiation - crosslinked , biodrgradable , synthetic hydrogels of this invention may be prepared by irradiating monomers or polymers , some or which are biodegradable or which contain biodegradable units or subunits . specific medical applications of these radiation - crosslinked , biodrgradable , synthetic hydrogels include applicatins wherein the hydrogel is used for hemostasis , tissue augmentation , tissue engineering , embolization , closure of vascular punctures or wounds and other medical applications .