Polyurethane　was　synthesized　by　the　reaction　of　isophorone　diisocyanate,　2-hydroxyethyl　methacrylate　and　diethylene　glycol.　Then　polyurethane　grafted　calcium　alginate　gel　material　was　prepared　via　freeradical　grafting　polymerization　with　azobisisobutyronitrile　as　an　initiator.　Modified　calcium　alginate　hydrogel　was　improved　in　thermal　property,　crystallinity　and　anti-swelling　properties.　The　reason　is　that　polyurethane　side　chains　affect　the　arrangement　of　calcium　alginate　by　forming　highly　ordered　crystal　region.　(C)　2014　Elsevier　B.V.　All　rights　reserved.