Heat Conduction Performance over a Poly(ethylene glycol) Self-Assembled Monolayer/Water Interface: A Molecular Dynamics Study
Heat Conduction Performance over a Poly(ethylene glycol) Self-Assembled Monolayer/Water Interface: A Molecular Dynamics Study
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DOI：
10.1021/acs.jpcb.0c09385
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发表时间：
2021-02-11
影响因子：
3.3
通讯作者：
Kikugawa, Gota
中科院分区：
文献类型：
--
作者：
Saha, Leton C.;Kikugawa, Gota
采用分子动力学模拟方法研究了聚乙二醇（PEG）自组装单分子膜（SAM）与水之间的界面热条件。结果发现，PEG SAM具有更高的热边界电导（TBC）比传统使用的烷烃为基础的SAM。TBC随PEG分子的长度有条件地变化，其中界面热阻是关键因素。我们的研究结果表明，TBC的PEG SAM/水界面的结构特性，而不是SAM终端和水之间的振动特性的匹配有很大的影响。结构分析表明，SAM末端氧原子周围的水结构对TBC的控制起着至关重要的作用。在这项研究中，自由体积的概念也已被利用，结果表明，自由体积分数的减少容纳了更高的TBC。通过计算PEG SAM的倾斜角和二面角、PEG链在水介质中的持久长度以及PEG SAM头基在金表面上的硫位置，使用定量扫描透射电子显微镜图像模拟，对实验数据精确地验证了该模型。
This study examined the interfacial heat condition between a poly(ethylene glycol) (PEG) self-assembled monolayer (SAM) and water using molecular dynamics simulation. It was found that the PEG SAM has higher thermal boundary conductance (TBC) than the traditionally used alkane-based SAM. The TBC conditionally varied with the length of the PEG molecules, where interfacial thermal resistance was a key factor. Our results reveal that the TBC of the PEG SAM/water interface is greatly influenced by its structural properties rather than the matching of vibrational properties between the SAM terminal and water. The structural analysis shows that the water structure around the terminal oxygen atom of the SAM plays a vital role in controlling the TBC. In this study, the concept of free volume has also been exploited, and the result suggests that the reduction of the free volume fraction accommodates a higher TBC. The model was precisely validated against experimental data by calculating the tilt angle and dihedral angle of the PEG SAM, the persistence length of the PEG chain in the water medium, and the sulfur position of the PEG SAM headgroup on the gold surface using quantitative scanning transmission electron microscopy image simulation.