A molecular dynamics study on heat conduction characteristics inside the alkanethiolate SAM and alkane liquid
A molecular dynamics study on heat conduction characteristics inside the alkanethiolate SAM and alkane liquid
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DOI：
10.1016/j.ijheatmasstransfer.2014.07.040
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发表时间：
2014-11
影响因子：
5.2
通讯作者：
G. Kikugawa;T. Ohara;T. Kawaguchi;I. Kinefuchi;Y. Matsumoto
中科院分区：
文献类型：
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作者：
G. Kikugawa;T. Ohara;T. Kawaguchi;I. Kinefuchi;Y. Matsumoto
在本研究中，我们进行了分子动力学（MD）模拟的自组装单层（SAM）和烷烃溶剂界面。特别是，1-十二烷乙烷（C12 H25 S单键）SAM化学吸附在金基板上接触正十二烷（C12 H26）溶剂进行了检查，比较内部SAM和溶剂相的传热机制从微观角度。非平衡MD（NEMD）模拟，其中施加一个恒定的热流通过SAM界面，进行。在这里，我们介绍了一种新的方法来澄清SAM和烷烃溶剂中的分子尺度热传导机制。这种方法使我们能够将宏观热通量分解为微观“构建块”，即，与分子运动相关的能量转移的贡献以及通过分子间（非键合）和分子内（共价键）相互作用进行的能量交换的贡献。有趣的是，我们已经清楚地表明，在SAM层内部，几乎所有的能量都是通过分子内相互作用沿沿着烷基链转移的。另一方面，内部的烷烃液体，分子内和分子间的相互作用有相似的贡献，总的热通量，尽管相同的分子结构和烷基链长度的SAM分子。这种热传导机制的显著差异源于SAM层中烷基链的有序结构。
In the present study, we performed molecular dynamics (MD) simulations of the self-assembled monolayer (SAM) and alkane solvent interface. In particular, 1-dodecanethiol (C12H25Ssingle bond) SAM chemisorbed on a gold substrate contacting withn-dodecane (C12H26) solvent was examined to compare the heat transfer mechanisms inside both the SAM and solvent phases from a microscopic viewpoint. The nonequilibrium MD (NEMD) simulation, in which a constant heat flux across the SAM interface was imposed, was performed. Here, we introduced the novel approach to clarify the molecular-scale mechanism on heat conduction in both SAM and alkane solvent. This approach enables us to decompose the macroscopic heat flux into the microscopic “building blocks”, i.e., the contribution of energy transfer associated with molecular motion and those of energy exchange by intermolecular (nonbonded) and intramolecular (covalent bond) interactions. Interestingly, we have obviously demonstrated that inside the SAM layer, almost all of the energy is transferred by the intramolecular interaction along the alkyl chain. On the other hand, inside the alkane liquid, the intramolecular and intermolecular interactions have similar contributions to the total heat flux in spite of the same molecular structure and alkyl chain length as the SAM molecules. This striking difference in heat conduction mechanism originates from the ordering structure of alkyl chains in the SAM layer.