APTES SAM制备过程及表面润湿性质的分子模拟研究

发布时间：2018-01-16 22:34

本文关键词：APTES SAM制备过程及表面润湿性质的分子模拟研究　出处：《浙江大学》2016年硕士论文　论文类型：学位论文

【摘要】：3-氨基丙基三乙氧基硅烷(3-aminopropyltriethoxysilane, APTES)自组装单分子膜(Self-assembled Monolayer, SAM)由于表面拥有氨基在基础研究和工程应用领域具有广泛的应用。但是迄今为止,文献中对APTES SAM的制备和性质争议颇多,对其自组装机制和内部结构仍不清楚。论文使用Materials Studio 6.1软件对APTES SAM的形成过程和表面润湿性质进行了分子模拟研究,揭示了APTES SAM的自组装机制和内部结构及其对表面润湿性质的影响。研究成果对APTES SAM的制备和研究具有重要意义。论文首先通过量子力学模拟揭示了APTES分子上三个乙氧基的水解机制和前后次序。研究表明,物理吸附到基底表面上的APTES分子上3号位乙氧基首先发生水解,生成的硅羟基立即与基底表面的羟基发生缩聚反应,共价键接固定到基底表面,随后APTES分子上2号位和1号位乙氧基再依次发生水解,APTES分子水解过程中所涉及的反应均为自发反应。在此基础上,论文采用分子模拟技术构建了可能存在的不同水解程度的APTES SAM结构模型,并对不同结构的APTES SAM表面润湿性质进行了研究。结果表明,对应水解一个、二个和三个乙氧基的APTES SAM表面的理论初始接触角分别为60°±30,50°±3°,40°±3°,水解两个乙氧基的APTES SAM表面理论前进接触角为46°±30。其中,水解两个乙氧基的APTES SAM表面接触角的理论模拟结果与Zeng等的实验结果完全吻合,印证了Zeng等提出的在目前技术条件下制备的APTES SAM中APTES分子上三乙氧基只有1-2个发生水解的结论。论文还对酸性催化剂作用下氨基质子化对APTES SAM成膜的影响和利用APTES分子在自组装过程中乙氧基未完全水解所形成的空间位阻构建均相混合SAM的可能性进行了实验和分子模拟研究,揭示了氨基质子化对上述过程的特殊影响。
[Abstract]:3-aminopropyltriethoxysilane. APTES) self-assembled monolayer Monolayer. SAM) has been widely used in basic research and engineering applications due to surface amino groups. However, the preparation and properties of APTES SAM have been controversial in the literature up to now. The self-assembly mechanism and internal structure are still unclear. This paper uses Materials Studio 6.1 software to analyze APTES. The formation process and surface wettability of SAM were studied by molecular simulation. The self-assembly mechanism and internal structure of APTES SAM and its influence on the surface wetting properties of APTES were revealed. The preparation and study of SAM is of great significance. Firstly, the mechanism and sequence of the hydrolysis of three ethoxyl groups on APTES molecules are revealed by quantum mechanical simulation. The ethoxy group at position 3 on the APTES molecule physically adsorbed on the substrate surface was hydrolyzed first, and the resulting silicon hydroxyl group immediately condensed with the hydroxyl group on the substrate surface, and the covalent bond was attached to the substrate surface. Then the reaction involved in the hydrolysis of APTES was spontaneous in turn at site 2 and position 1. On the basis of that, the reaction involved in the hydrolysis of APTES was spontaneous. In this paper, molecular simulation technique was used to construct APTES SAM structure model with different hydrolysis degree. The wetting properties of APTES SAM with different structures were studied. The theoretical initial contact angles of two and three ethoxyl APTES SAM surfaces are 60 掳卤30 掳卤3 掳50 掳卤3 掳and 40 掳卤3 掳respectively. The forward contact angle of APTES SAM surface for hydrolysis of two ethoxy groups is 46 掳卤30. The theoretical simulation results of the surface contact angle of APTES SAM hydrolyzed by two ethoxy groups are in good agreement with the experimental results of Zeng et al. It is confirmed that the APTES prepared under the present technical conditions proposed by Zeng et al. Only 1 or 2 triethoxy groups on the APTES molecule in SAM were hydrolyzed. In this paper, the effect of protonation of Amino group on APTES under the action of acid catalyst was also discussed. The influence of SAM film formation and the possibility of constructing homogeneous mixed SAM by using the steric hindrance formed by the incomplete hydrolysis of APTES molecules in the process of self-assembly were studied experimentally and numerically. The special effect of aminoprotonation on the above process is revealed.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O647

【相似文献】