The Preparation And Biologic Performance Research Of Polyurethane Porous Coating On The Surface Of 316L Stainless Steel

In order to decrease the vas restenosis and to improve the biological compatibility, drug-elute-stents have been applied at clinic. In this research, our intention was to alter the surface characterization of 316L stainless steel (316LSS). The main method was that polyurethane (PU) coatings with excellent mechanism property and perfect blood compatibility were prepared on the 316LSS surface.In our work, the PU porous coating was prepared by wet-phase inversion. It is observed that pore diameter larger and larger as air relative humidity increasing and solution concentration decreasing. In the preparation procedure of PU coatings, the pore diameter could be changed in the range of 3-4μm to 30μm by controlling the relative humidity and the solution concentration.In the formation process of PU coatings, the soft-segment presents on the surface, and hard-segment adheres on the bottom because of PU micro-phase inversion. The Fourier Transition Infrared Ray (FTIR) Spectra shows that the PU belongs to polyether. PU dense coatings contain dissociating -NH-, but PU porous coatings consist hydrogen-bonded -NH-and saturated alkyl -CH3-. The X-Ray results proves that crystalloid takes on the surface of PU dense coatings, but the top-layer of porous coatings is amorphous And the examination of hydrophilic and hydrophobic property indicates that PU porous coating is super-hydrophobic because more soft-segments cover on the surface. All of these point out that the coating configuration is different, the components is also different. In addition, due to the larger contact angle of PU porous coating, the bonding energy is lower than that of PU dense coating and 316LSS. Generally speaking, it is diffcult to conglutinate blood using porous coating because of the lower bonding energy.In this paper, the heamcompatibility was investigated by the test of platelet adhesion and the trail of dynamic-clotting blood. The results show that, compared with 316LSS, PU porous coating reduce the amount of platelet deposited on the surface, and prolong the time of blood clot due to the surface chemical bond. The soft-segments on the surface of PU porous coating enhance the albumin absorption, and take from the absorption of fibrinogen and decrease the destruction to red blood cell. All of these testify that PU porous coating has more perfect heamcompatibility.