Sano Hikaru, Maeda Hajime, Ichii Takashi, Murase Kuniaki, Noda Kei, Matsushige Kazumi, Sugimura Hiroyuki
Department of Materials Science and Engineering, Kyoto University Yoshida-hommachi, Sakyo-ku, Kyoto 606-8501, Japan.
Langmuir. 2009 May 19;25(10):5516-25. doi: 10.1021/la804080g.
For practical application of self-assembled monolayers (SAMs), knowledge of their chemical durability in acidic or basic solutions is important. In the present work, a series of SAMs directly immobilized on a silicon (111) surface through Si-C or Si-O-C covalent bonds without a native oxide layer were prepared by thermally activated chemical reactions of a hydrogen-terminated Si(111) substrate with linear molecules, i.e., 1-hexadecene, 1-hexadecanol, 1-dodecanol, and n-dodecanal, to investigate the durability of the SAMs to HF and Na2CO3 solutions. While grazing incidence X-ray reflectivity measurements showed that all the as-prepared SAMs had almost the same film density and molecular coverage, keeping the original step and terrace structure of Si(111) as is observed by atomic force microscopy, they gave different degradation behaviors, i.e., pitting and concomitant surface roughening in both solutions. 1-hexadecene SAM was stable against immersion in both solutions, while the other SAMs were damaged within 60 min, most likely due to the difference in chemical bonding modes at the SAM/Si interface, i.e., Si-C and Si-O-C.
对于自组装单分子层（SAMs）的实际应用而言，了解它们在酸性或碱性溶液中的化学耐久性非常重要。在本工作中，通过氢终止的Si(111)衬底与线性分子（即1-十六烯、1-十六醇、1-十二醇和正十二醛）的热活化化学反应，制备了一系列通过Si-C或Si-O-C共价键直接固定在无原生氧化层的硅(111)表面上的SAMs，以研究SAMs对HF和Na2CO3溶液的耐久性。掠入射X射线反射率测量表明，所有制备好的SAMs具有几乎相同的膜密度和分子覆盖率，保留了原子力显微镜观察到的Si(111)的原始台阶和平台结构，但它们表现出不同的降解行为，即在两种溶液中都出现点蚀并伴随表面粗糙化。1-十六烯SAM在两种溶液中浸泡时都很稳定，而其他SAMs在60分钟内就受到了损坏，这很可能是由于SAM/硅界面处化学键合模式的差异，即Si-C和Si-O-C。
