Surface modification of shape memory alloys with bio-functional polymers for medical application

1.钛镍合金的超弹性（1）通过拉伸试验和DSC分析，研究了适合于室温超弹性的钛镍合金成分。发现Ti-50.85Ni（摩尔%）附近的成分适合于该目的。(2)It结果表明，提高Ti-Ni合金力学性能的热处理工艺条件为713~773K，保温0.9ks。（3）钛镍合金铸件的疲劳强度与纯钛或Ti-6Al-4V合金铸件相似;（2）合金支架的设计与制作在自膨式超弹性支架基本设计的基础上，采用激光微切割技术制备了钛镍合金管支架模型;（3）钛镍合金表面生物功能聚合物涂层合成具有0.30 MPC摩尔分数（PMB 30）的MPC-共-BMA作为用于涂层的血液相容性MPC聚合物合金。（2）采用旋涂法在Ti-Ni合金表面涂覆PMB 30。结果表明，PMB 30涂层的边缘部分并不均匀，但涂层厚度随浸泡时间的增加而减小，在盐水溶液中浸泡72 h后，涂层厚度稳定在15-20 nm。4. Ti-Ni合金的表面改性（1）Ti-Ni合金表面氧化层厚度增加，通过电解处理，层中的钛被氧化成Ti ^<4 +>，并且变得更加稳定。（2）电解处理后，表面氧化层中的镍浓度降低，尤其是用甘油、乳酸和水组成的电解质进行GLW处理后，表面氧化层中的镍浓度降低。该处理有效地提高了Ti-Ni合金的耐腐蚀性，因此可以开发出新型安全的医疗器械，包括在机械功能、血液相容性和耐腐蚀性方面具有上级性能的支架。

1.Super-elasticity of Ti-Ni alloy(1)Composition of Ti-Ni alloy suitable for super-elasticity at body temperature was investigated by tensile test and DSC. It was found that the composition around Ti-50.85Ni (mol%) was suitable for the purpose.(2)It was found that the heat treatment condition effective to improve the mechanical property of Ti-Ni alloy was between 713 and 773 K for about 0.9 ks.(3)Fatigue strength of the alloy castings was evaluated to be similar to those of CP titanium or Ti-6A1-4V alloy castings.2.Design and fabrication of the alloy stentsStent models were fabricated with Ti-Ni alloy tubes by laser micro-cutting method based on the basic design of self-expanding type stent with super-elasticity.3.Coating on Ti-Ni alloy with bio-fuctional polymers(1)Poly (MPC-co-BMA) with a 0.30 MPC mole fraction (PMB 30) was synthesized as a blood compatible MPC polymer alloy for coating.(2)PMB 30 was coated on the surface of Ti-Ni alloy specimens by spin coating. As the result, the PMB 30 coating layer was not uniform at the marginal part, however, the thickness of the layer decreased with increasing immersion period and became stable at 15-20 nm after 72 h immersion in saline solution.4.Surface modification of Ti-Ni alloy(1)Thickness of the surface oxide layer of Ti-Ni alloy increased, and titanium in the layer was oxidized to Ti^<4+> and became more stable by electrolytic treatment.(2)Nickel concentration in the surface oxide layer decreased after electrolytic treatment, especially by the GLW treatment with the electrolyte composed of glycerol, lactic acid, and water. This treatment was effective in improving the corrosion resistance of Ti-Ni alloy.It was concluded that it was possible to develop new and safe medical devices including stents with superior property in mechanical function, blood compatibility, and corrosion resistance.