Synthesis And Surface Modification Of Crosslinked Polyurethane Elastomer For Improving Its Hemocompatibility

Polyurethane (PU) as a kind of biomedical polymeric material has extensiveapplied foreground. In this study, in order to improve the hemocompatibility ofpolycarbonateurethane, the crosslinked polycarbonateurethane was synthesized. Thenthe phosphorylcholine glyceraldehyde (PCGA) was grafted onto the surface of PCUfilms via a three-step procedure.In this paper, polyether polyol (TMN-1000) and polycarbonate diol (PCDL) wereused as soft segment, isophorone diisocyanate (IPDI) as hard segment,1,4-butanediol(BDO) as chain extender, and dibutyltin dilaurate (DBTDL) as catalyst to synthesizepre-polycarbonateurethane successfully by pre-polymerization method. Then, IPDIand polymerized HDI (HHDI) were used as crosslinker to synthesize cross-linkedpolycarbonateurethane with different proportion and in different way. Attenuated totalreflectance flourier transform infrared spectroscopy (ATR-FTIR), differentialscanning calorimetry (DSC) and microcomputer controlling tensile testing machinewere used to characterize the cross-linked polycarbonateurethane. The ATR-FTIRresults showed that a lot of urethane groups were found in structure of thecross-linked polycarbonateurethane and a micro-phase separation structure was foundby the DSC. The mechanical properties analysis indicated that the tensile strength andtensile rate of the cross-linked polycarbonateurethane were not only relevant with thefeeding methods, but also with the ingredients.In the following report, a multi-step covalent method was used to improve thehemocompatibility of the PCU.1,6-Hexamethylene diisocyanate (HDI) was graftedonto the PCU film to act the film surface. Then, phosphorylcholine glyceraldehydes(PCGA) were linked to PCU surface using1,6-hexanediamine (HDA) andamino-poly(ethylene glycol)(APEG) as spacers. X-ray photoelectron spectroscopy(XPS) and X-ray fluorescence spectrometer (XRF) analysis of the modified filmsindicated that PCGA had already been covalently linked to the PCU surface. Watercontact angle test showed that the surface hydrophilicity has been improved after thesurface of PCU film was modified. Topographies of the blank and modified PCU films were studied using AFM and the results implied that the micro-structure of themodified PCU was changed and meanwhile the roughness was increased.To evaluate the interactions between blood and modified PCU films, plateletadhesion experiments were performed in this study. Scanning electron microscopy(SEM) observation of the PCU films after treated with platelet-rich plasmademonstrated that the lots of platelets adhesion were observed on the blank PCU filmand the platelets had been activated. However, platelets rarely adhered to the surfaceof the modified PCU films and moreover, the adhered platelets had not been activated.The platelet adhesion result indicated that the modified PCU films could improve thehemocompatibility of the PCU film obviously.