Biomedicalsegmentedpolyetherurethane(SPEU)elastomersarecompositepoly-merswithmicrophaseseparationstructure.VariousattemptsofintroducingionicgroupsintoSPEUhavebeencarriedoutfortheimprovementoftheirbloodcompati-bilities.Weherereportthemechanicalandanticoagulantproperties.Twoseriesofsulfooctylpendantgroupscontainingsegmentedpolyetherurethaneswithwelldefinedfinestructurehavebeensynthesizedinourlab-oratory.ThesulfooctylgroupswereexactlylocatedatthehardsegmentswhentheSPEUswerepreparedfromthereactionofpolytetramethyleneglycol(PTMG)1000-4,4’diphenylmethanediisocyanate(MDI)oligomerswithN-sulfoalkyldiethanolamine