Surface modification of silicon oxide with trialkoxysilanes toward close-packed monolayer formation.
Surface modification of silicon oxide with trialkoxysilanes toward close-packed monolayer formation.
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DOI：
10.1021/la4009834
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发表时间：
2013-05
期刊：
影响因子：
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通讯作者：
Mutsuo Tanaka;T. Sawaguchi;M. Kuwahara;O. Niwa
中科院分区：
文献类型：
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作者：
Mutsuo Tanaka;T. Sawaguchi;M. Kuwahara;O. Niwa
为了考察三烷氧基硅烷形成致密单层的潜力，对氧化硅进行了表面改性，使三烷氧基硅烷带有二茂铁基团，并用电化学方法进行了分析。由于发现端氢硅在有机溶剂中与三烷氧基硅烷发生自然氧化反应，其中氧化硅层足够薄，可以为电化学分析提供导电性，因此将端氢硅片浸入三烷氧基硅烷溶液中进行表面改性而不进行氧化处理。在不同温度、浓度、溶剂和分子结构条件下，循环伏安法测定了固定二茂铁硅烷在硅表面的表面浓度，并研究了循环伏安图中的阻断效应，以深入了解密度导致致密层的形成。结果表明，二茂铁硅烷烷基链较长时，在较温和的条件下容易发生单层修饰，并形成紧密堆积层，表现出明显的阻隔效应。然而，即使固定二茂铁硅烷的表面浓度大于单层的预期浓度，表面修饰也会继续进行。根据这些趋势，三烷氧基硅烷修饰的氧化硅表面虽然形成了致密的层，但可以认为是部分多层而不是单层。与二茂铁-重氮修饰的碳表面相比，当固定二茂铁部分的表面浓度低于二茂铁-硅烷修饰的氧化硅时，可以观察到明显的阻塞效应。
In order to scrutinize potential of trialkoxysilanes to form close-packed monolayer, surface modification of silicon oxide was carried out with the trialkoxysilanes bearing a ferrocene moiety for analysis by electrochemical methods. As it was found that hydrogen-terminated silicon reacts with trialkoxysilane through natural oxidation in organic solvents, where the silicon oxide layer is thin enough to afford conductivity for electrochemical analysis, hydrogen-terminated silicon wafer was immersed in trialkoxysilane solution for surface modification without oxidation treatment. Cyclic voltammetry measurements to determine surface concentrations of the immobilized ferrocene-silane on silicon surface were carried out with various temperature, concentration, solvent, and molecular structure, while the blocking effect in the cyclic voltammogram was investigated to obtain insight into density leading to the close-packed layer. The results suggested that a monolayer modification tended to occur under milder conditions when the ferrocene-silane had a longer alkyl chain, and formation of a close-packed layer to show significant blocking effect was observed. However, the surface modification proceeded even when surface concentration of the immobilized ferrocene-silane was greater than that expected for the monolayer. On the basis of these tendencies, the surface of silicon oxide modified with trialkoxysilane is considered to be a partial multilayer rather than monolayer although a close-packed layer is formed. This result is supported by the comparison with carbon surface modified with ferrocene-diazonium, in which a significant blocking effect was observed when surface concentrations of the immobilized ferrocene moiety are lower than that for silicon oxide modified with ferrocene-silane.