Surface structure of binary self-assembled monolayers formed by electrochemical selective replacement of adsorbed thiols
Surface structure of binary self-assembled monolayers formed by electrochemical selective replacement of adsorbed thiols
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DOI：
10.1021/la981631y
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发表时间：
1999-07-20
期刊：
影响因子：
3.9
通讯作者：
Kakiuchi, T
中科院分区：
文献类型：
--
作者：
Hobara, D;Sasaki, T;Kakiuchi, T
利用扫描隧道显微镜（STM）和循环伏安法研究了通过电化学选择性置换相分离的二元硫醇自组装膜（SAMs）中吸附的硫醇制备的二元硫醇自组装膜的纳米尺度结构。采用相分离的1-十一烷醇（UDT）和3-巯基丙酸（MPB）二元SAM作为起始体系。MPA，其具有较小的负解吸电位，通过控制电极电位被选择性地除去，并被1-十六烷硫醇（HDT）或11-巯基十一烷酸MUA取代。选择性去除MPA后剩余的UDT层的STM图像表现出两种类型的域：具有条纹结构的域和硫醇分子密集堆积的域，这表明一些UDT分子被重新取向并形成低密度区域，其中分子在表面上平坦排列。通过置换形成的UDT-HDT和UDT-MUA二元自组装膜的STM图像显示了纳米尺度的相分离表面。置换后的畴大小约等于初始相分离的UDT-MPA SAM的畴大小，表明畴大小不受置换的显著影响。
Nanometer-scale structure of binary thiol self-assembled monolayers (SAMs) prepared by the electrochemical selective replacement of adsorbed thiols in phase-separated binary SAMs has been studied by scanning tunneling microscopy (STM) and cyclic voltammetry. A phase-separated binary SAM of 1-undecanethiol (UDT) and 3-mercaptopropionic acid (MPB) is used as a starting system. MPA, which has a less negative desorption potential, is selectively removed by controlling the electrode potential, and replaced with 1-hexadecanethiol (HDT) or 11-mercaptoundecanoic acid MUA. STM images of the UDT layer remaining after the selective removal of MPA exhibit two types of domains: domains with striped structure and domains where thiol molecules are densely packed, suggesting that some UDT molecules are reoriented and form low-density regions where the molecules are aligned flat on the surface. STM images of UDT-HDT and UDT-MUA binary SAMs formed by the replacement show surfaces which are phase-separated in nanometer scale. The size of the domains after the replacement is approximately equal to that of the initial phase-separated UDT-MPA SAM, indicating that the domain size is not significantly affected by the replacement.