A molecular dynamics study on heat transfer characteristics at the interfaces of alkanethiolate self-assembled monolayer and organic solvent

Abstract

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.

A Molecular Dynamics Study on Heat Transfer Characteristics Over the Interface of Self-Assembled Monolayer and Water Solvent

“…These studies evaluated the effect of SAM modification on interfacial thermal transport properties and made it clear how SAM species, SAM terminal groups, and affinity between SAM and the solvent impact on the TBC. Our group suggested that the surface modification of SAM enables to significantly increase TBC at the interface between the gold substrate and toluene organic liquid [12]. Our group suggested that the surface modification of SAM enables to significantly increase TBC at the interface between the gold substrate and toluene organic liquid [12].…”

“…So far, there have been studies on the heat conduction over the SAM-solvent interfaces [10][11][12][13][14][15]. These studies evaluated the effect of SAM modification on interfacial thermal transport properties and made it clear how SAM species, SAM terminal groups, and affinity between SAM and the solvent impact on the TBC.…”

Heat conduction mechanisms in nanofluids and suspensions

“…Heat conduction can be mediated by translational, vibrational, and rotational modes of the molecules composing the liquid and conduction within the molecules themselves, especially in organic liquids with long molecular chains [60]. In most liquids, thermal conductivity increases as temperature decreases, while the opposite trend is observed in water [61,62].…”

Spectral mapping of heat transfer mechanisms at liquid-solid interfaces

“…Molecular dynamics (MD) simulations have been used to investigate the effects of, e.g., liquid-solid bonding strength [13][14][15][16], temperature [17], pressure [18], surface roughness [19,20], surface patterning [21], and surface functionalization [22][23][24][25] on the interfacial conductance. Detailed analysis of heat transfer mechanisms at solid-liquid interfaces is, however, still lacking, mostly due to the nonexistence of simplifying small-displacement approximations allowing for extracting frequency-dependent mode transmission functions as in stiff solid-solid surfaces (see, e.g., Refs.…”