A molecular dynamics study on thermal boundary resistance over the interfaces of self assembled monolayer and solvent

In this paper, we perform molecular dynamics (MD) simulations of the interfaces composed of the self assembled monolayer (SAM) and organic solvent in order to investigate the interfacial heat transfer characteristics of SAMs from the microscopic viewpoint. Archetypal SAMs, i.e., alkanethiol molecules chemically adsorbed on Au (111) substrate, and toluene solvent are adopted for the computational system. Two alkanethiols with different chain lengths, that is, I propanethiol (C₃H₇SH) and 1 dodecanethiol (C ₁₂H₂₅SH), are used for SAM interface systems. In addition to the SAM interfaces, bare solid substrate without SAM are examined for comparison of the heat transfer characteristics. Nonequilibrium MD (NEMD) simulations in which a temperature gradient is imposed across the interface are performed and the interfacial thermal resistance in each system is discussed. As a result, it is shown that the SAM solvent interfaces have the smaller thermal resistance as compared with that at the bare Au interface. In order to investigate the mechanisms of the small resistance at SAM solvent interface, a vibrational character of molecules in the interface region and an adsorbed structure of solvent molecules are discussed.