Vapor-phase grafting of functional silanes on atomic layer deposited Al2O3
Vapor-phase grafting of functional silanes on atomic layer deposited Al2O3
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DOI：
10.1116/6.0002364
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发表时间：
2023-04
期刊：
影响因子：
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通讯作者：
Vepa Rozyyev;Rahul Shevate;R. Pathak;Julia G. Murphy;A. Mane;S. Sibener;J. Elam
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文献类型：
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作者：
Vepa Rozyyev;Rahul Shevate;R. Pathak;Julia G. Murphy;A. Mane;S. Sibener;J. Elam
需要进行基础研究，以提高我们对水环境中选择性吸附的理解，并开发更有效的水处理吸附剂和过滤器。功能化硅烷的气相接枝是制备良好定义表面以研究选择性吸附的有效方法。在本研究中，我们在原子层沉积制备的氧化铝（Al2O3）表面进行了五种不同硅烷化合物的气相接枝。这些硅烷化合物的通式为L3Si-C3H6-X，其中配体L控制与羟基化Al2O3表面的反应性，功能部分X决定接枝层的表面性质。我们使用原位傅里叶变换红外光谱和非原位x射线光电子能谱测量来研究接枝过程，并使用扫描电子显微镜、原子力显微镜和水接触角测量来表征表面。我们发现接枝的氨基硅烷的结构和密度受其化学反应性和硅原子周围的空间约束以及锚定官能团的性质的影响。在较高的接枝温度下，甲基取代氨基硅烷产生了更高表面密度的疏水表面。还研究了巯基硅烷和腈基硅烷，并与氨基硅烷端面进行了比较。通过原子力显微镜的测量证实，氧基硅烷具有均匀的单层涂层，而氯硅烷具有不均匀的涂层。
Fundamental studies are needed to advance our understanding of selective adsorption in aqueous environments and develop more effective sorbents and filters for water treatment. Vapor-phase grafting of functional silanes is an effective method to prepare well-defined surfaces to study selective adsorption. In this investigation, we perform vapor phase grafting of five different silane compounds on aluminum oxide (Al2O3) surfaces prepared by atomic layer deposition. These silane compounds have the general formula L3Si–C3H6–X where the ligand, L, controls the reactivity with the hydroxylated Al2O3 surface and the functional moiety, X, dictates the surface properties of the grafted layer. We study the grafting process using in situ Fourier transform infrared spectroscopy and ex situ x-ray photoelectron spectroscopy measurements, and we characterize the surfaces using scanning electron microscopy, atomic force microscopy, and water contact angle measurements. We found that the structure and density of grafted aminosilanes are influenced by their chemical reactivity and steric constraints around the silicon atom as well as by the nature of the anchoring functional groups. Methyl substituted aminosilanes yielded more hydrophobic surfaces with a higher surface density at higher grafting temperatures. Thiol and nitrile terminated silanes were also studied and compared to the aminosilane terminated surfaces. Uniform monolayer coatings were observed for ethoxy-based silanes, but chlorosilanes exhibited nonuniform coatings as verified by atomic force microscopy measurements.