TiNi形狀記憶合金以脈衝電漿沉積HMDSN薄膜之研究

Abstract

本研究以TiNi形狀記憶合金為基材使用六甲基二矽胺(Hexamethyldisilazane, HMDSN)單體以脈衝式電漿輔助化學沉積法 (PECVD) 沉積非晶質SiC:H薄膜於TiNi合金之上並利用UV 光誘導接枝聚合丙烯醯胺(Acrylamide, AAm)單體，改變薄膜表面官能基，做酵素固定使TiNi合金成為具抗凝血生化特性之生醫材料。薄膜沉積速率快，表面形貌均勻、孔洞少、粗糙度低均在2~4nm之間。並顯著地提升抗腐蝕性，使腐蝕電流密度下降約至少四個數量級。由FTIR所得之吸收光譜，可知Si-C 與C-H等鍵結受破壞，形成Si-H與C=O等鍵結，沉積出高度分支且交錯連結之薄膜。經歷UV 光誘導接枝聚合AAm後，由FTIR光譜可證明成功接枝，表面粗糙度下降至1-2nm，形成新的ㄧ層緻密有機薄膜。接枝後水接觸角由87°下降至36°，與玻璃之相對濕摩擦係數由0.25下降至0.2以下，有利生醫方面之應用。後續經歷固定肝素之處理後，可觀察到聚合鍵結之肝素分子形成之團聚物，且由XPS可偵測出S元素存在為肝素固定之證明。

SiC:H organic-like thin films are deposited on TiNi shape memory alloy (SMA) by DC-pulsed plasma enhanced chemical vapor deposition (PECVD) of HMDSN and Ar gas mixtures at room temperature. The organic-like thin films containing peroxides or free radicals can be subsequently grafted with hydrophilic polymer acrylamide (AAm) by UV-induced grafting polymerization. Heparin is immobilized onto grafted-AAm thin films to take TiNi SMA into the anti-thrombin biomaterials. The deposition rate of the plasma-polymerized HMDSN (PPHMDSN) thin film is fast and the root mean square surface roughness is between 2~4 nm. The PPHMDSN thin films not only enhance the corrosion resistance but make the corrosion current density decay four orders. Based on the micro-FTIR spectra, the Si-C and C-H bonds of the original HMDSN monomer are destroyed and new Si-H and C=O bonds are formed. The success of grafting is proved by FTIR. After grafting polymerization of AAm, a new dense organic thin films layer is formed in which the water contact angle decreases from 87° to 36° and the friction coefficient becomes lower. These properties are beneficial to the biomedical applications. According to XPS, the element S can be detected to prove that heparin is covalently immobilized on TiNi SMA.