MODIFICATION OF SURFACE REACTIVITIES ON SILICA (1000) AS MODELS OF BIOADHESION

提出了有机硫化合物在二氧化硅表面的粘附性研究。这项工作定义了一种以前未知的将碳氢化合物与二氧化硅表面结合的模式。接枝在表面上的分子的化学反应是表面科学日益关注的问题。这些系统以红外透射和固态核磁共振为特征，与生物粘附直接相关——细菌粘附在膜上的物理和化学相互作用，或白细胞粘附在生物植入物上。有四个主要目标：1。二氧化硅表面新反应（100012）。我们将有机硫化合物与加热到1000摄氏度的二氧化硅表面在高真空中反应。例如，硫醇产生含有S-Si键的硫代硅氧烷膜。2.双功能分子在二氧化硅上的表面接枝（1000）。将接枝含有与二氧化硅（1000）反应的有机硫头基和暴露在表面的末端官能团的双功能分子。第二官能团必须要么不与二氧化硅（1000）发生反应，要么被化学保护以免发生这种反应。例如，在双功能分子中，如卤化烷硫醇，Cl-(CH2)nSH， S和Cl都可能与表面硅氧烷相互作用。三功能半胱氨酸可以通过其SH基团通过酯化保护羧酸酯和烷基化保护胺而被完全吸收。3. 原位反应。目的是制备不能通过吸收双功能分子直接制备的表面官能团。第一个实验将是上述2中提到的保护基团的脱烷基和水解。另一个研究将是醛端代硫硅氧烷薄膜的制备；吸附质前驱体C=O (CH2)nSH是合成不可接近的。这家公司对金属的配合能力较弱。4. 吸附物-与改性表面的相互作用。对界面分子环境的研究揭示了影响表面-吸附物相互作用的基本因素。我们将系统地改变烷基链长度和链末端，以影响表面吸收性能的空间和化学控制。这些影响将通过可控大气环境的光谱研究来探讨，例如可逆吡啶配位。

A study of the adhesion of organosulfur compounds at the surface of silica is proposed. This work defines a previously unknown mode of binding hydrocarbon to the surface of silica. Chemical reactions of molecules grafted on surfaces are of growing interest in surface science; these systems, characterized by IR transmission and solid state NMR, have direct relevance to bioadhesion--the physical and chemical interactions of bacteria adhering to membrane, or white blood cells adhering to bioimplants. There are four major targets: 1. New surface reactions on Silica (100012). We will react organosulfur compounds with the surface of silica heated to 1000C in high vacuum. For example, a thiol gives a thiosiloxane film containing the S-Si bond. 2.Surface Grafting of Bifunctional Molecules on Silica (1000). Bifunctional molecules, containing the organosulfur head group to react with the silica (1000) and a terminal functional group exposed at the surface will be grafted. The second functionality must either not react with the silica (1000) or be chemically protected from such reaction. For example, in a bifunctional molecule such as a halogenated alkanethiol, Cl-(CH2)nSH, both the S and the Cl could potentially interact with surface siloxanes. Trifunctional cysteine could be absorbed exclusive through its SH group by protecting the carboxylate through esterification and the amine through alkylation. 3. In-situ reactions. The goal is to prepare surface functionalities which could not be prepared directly from absorption of bifunctional molecules. Dealkylation and hydrolysis of protected groups referred to in 2 above will be the first experiments. Another examine would be preparation of an aldehyde terminated thiosiloxane film; the adsorbate precursor C=O (CH2)nSH is synthetically inaccessible. This firm may weakly coordinate /adhere metals. 4. Adsorbate-Interactions with the Modified Surfaces. Studies of the molecular environment at the interface reveal the fundamental factors affecting surface-adsorbate interactions. We will vary systematically the alkyl chain length and the chain terminus to effect steric and chemical control of the surface's absorption properties. These effects will be probed with spectroscopic studies of controlled atmosphere environments such as e.g. reversible pyridine coordination.