Abstract: At the molecular level, it is believed that polymers containing zwitterionic structure should be more compatible with blood. The films of polyether-urethane were constructed with sulfoammonium zwitterionic structure by a three-step procedure. In the first step, the film surfaces were treated with hexam-ethylene diisocyanate(HDI) in toluene at 50 'Cin the presence of dibutyltin dilaurate(DBTDL) as a catalyst. The extent of the reaction was measured by ATR-IRspectra. Amaximum number of NCOgroups were obtained in about 90 min reaction. In the second step, the hydroxy groups of N, N-dimethylethylethanolamine (DMEEA) were allowed to react in toluene with surface bound isocyanate groups. In the third step, sulfoammonium zwitterionic structures were constructed onto the surface through the ring-opening reaction between tertiary amine constructed by the second step and 1,3-propane-sultone(PS). The surface was characterized by ATR-IR and XPS, and as anticipated, the sulfoammonium structure was constructed on the PU films. The platelet adhesion test revealed that films attached to sulfoammonium zwitterionic structure showed an excellent anti-platelet adhesion. These good results are due to the interfacial sulfoammonium zwitterionic structure.

Key words: Polyether-urethane, Sulfoammonium zwitterionic structure, Surface modification, Platelet ad- hesion, Nonthrombogenic biomaterials