Kikugawa Gota, Ohara Taku, Kawaguchi Toru, Torigoe Eiichi, Hagiwara Yasumasa, Matsumoto Yoichiro
Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
J Chem Phys. 2009 Feb 21;130(7):074706. doi: 10.1063/1.3077315.
In this paper, we present molecular dynamics (MD) simulations of interfaces composed of self-assembled monolayers (SAMs) and solvents in order to investigate the heat transfer characteristics at the interface. Two typical normal alkylthiolate SAMs with different chain lengths, i.e., 1-propanethiol C(3)H(7)SH and 1-dodecanethiol (C(12)H(25)SH) chemically adsorbed on Au(111) substrate surfaces, were used, and toluene was adopted as the organic solvent. In addition to the SAM systems, an interface composed of the bare solid substrate and solvent (without SAMs) was analyzed for comparison. Nonequilibrium MD simulations, in which a temperature gradient perpendicular to the interface was imposed, were performed and the difference in thermal boundary resistance in the interface systems was discussed. We observed that the SAM interfaces have smaller thermal resistance when compared with that of the bare solid interface. In order to understand the mechanisms of the small resistance at the SAM-solvent interfaces, the vibrational character of molecules in each phase, which contacted each other at the interface was analyzed and a detailed adsorbed structure of solvent molecule in the interface region was extracted. As a result, a clear difference in these characters was found between the SAM interfaces and bare solid interface.
在本文中，我们进行了由自组装单分子层（SAMs）和溶剂组成的界面的分子动力学（MD）模拟，以研究界面处的传热特性。使用了两种具有不同链长的典型正烷基硫醇盐自组装单分子层，即化学吸附在Au(111)衬底表面上的1-丙硫醇C(3)H(7)SH和1-十二烷硫醇（C(12)H(25)SH），并采用甲苯作为有机溶剂。除了自组装单分子层体系外，还分析了由裸露的固体衬底和溶剂（无自组装单分子层）组成的界面以作比较。进行了非平衡分子动力学模拟，其中施加了垂直于界面的温度梯度，并讨论了界面体系中热边界电阻的差异。我们观察到，与裸露的固体界面相比，自组装单分子层界面具有更小的热阻。为了理解自组装单分子层-溶剂界面处小电阻的机制，分析了在界面处相互接触的各相中分子的振动特性，并提取了界面区域中溶剂分子的详细吸附结构。结果，在自组装单分子层界面和裸露的固体界面之间发现了这些特性的明显差异。
