Construction of sulfoammonium zwitterionic structure onto surface of polyurethane by hexamethylene diisocyanate (HDI) spacer for improving blood compatibility

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 hexamethylene diisocyanate(HDI) in toluene at 50 degreesC in the presence of dibutyltin dilaurate(DBTDL) as a catalyst. The extent of the reaction was measured by ATR-IR spectra. A maximum number of NCO groups 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.