The Research Of Large-Area Regular Array Microporous Polymer Films On Medical Metal Surface

In this research, our intention is to alter the surface characterization of medical metal 316L stainless steel (316LSS). The main method is that PLGA coatings with excellent structure of pore morphology and perfect blood compatibility are prepared on the 316LSS surface in order to decrease the vas restenosis and do some basic research for the endotheliumalization-stent.In our work, the PLGA porous coating is prepared on the 316LSS surface by water-assisted fabrication theory through dip-coating method instead of the coating method which is not convenient to prepare film on surface with complicated structure. We study the formation rule and mechanism of the regular array microporous polymer films. It is concluded that the polymer molecular weight and the concentration are the main factors to influent the layer's morphology. It was prone to form regular structure up the critical concentration and to form the pore morphology like polygon structure under the critical concentration at the same molecular weight. The humidity and the pulling-speed have no obvious impact on the morphology of the films.The pore diameter is 1～10μm for the regular array: they are decreased with the raise of the concentration at low molecular weight and increased with the raise of the concentration at high molecular weight; they are increased with the raise of the humidity; they are little increased with the raise of pulling-speed.The Marangoni convection and the capillary force are the main factors to effect the formation of the array. The morphology like polygon structure was formed by the Marangoni convection influence when Ma＞80, and the capillary force control the layer to be the regular porous morphology when Ma＜80.We use the method of contact angle measurement to token the layer's hydrophilic and hydrophobic property. The porous layer shows the hydrophobic property due to the contact angle of the porous layer(103.3°)is less than that of the PLGA compact layer(73.6°). And the contact angle increased with the decrease of the pore diameter. Generally speaking, it is difficult to conglutinate blood using porous coating because of the lower bonding energy.In this paper, the bloodcompatibility was investigated by the test of platelet adhesion and the trail of dynamic-clotting blood. The results show that, compared with 316LSS, PLGA porous coating reduce the amount of platelet deposited on the surface, and prolong the time of blood clot. For the porous layers, the platelets are difficult to adhere to the layer when the pore diameter is similar to the diameter of platelets because of the platelets can not to enter into the pores, and then improve the re-cruor property due to this surface structure.We also try to prepare the nano-multilayer on the PLGA porous film by deposition process of electrostatic self-assembly, and want to improve the biocompatibility of the microporous polymer films.