Molecular Structure Effect of a Self-Assembled Monolayer on Thermal Resistance across an Interface

Understanding heat transfer across an interface is essential to a variety of applications, including thermal energy storage systems. Recent studies have shown that introducing a self-assembled monolayer (SAM) can decrease thermal resistance between solid and fluid. However, the effects of the molecu...

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Autores principales:	Lijian Song, Youchen Zhang, Weimin Yang, Jing Tan, Lisheng Cheng
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	molecular dynamic simulation coarse-grained thermal resistance self-assembled monolayer PEG Organic chemistry QD241-441
Acceso en línea:	https://doaj.org/article/f3e0b08a150242019e166d12206b3602
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spelling	oai:doaj.org-article:f3e0b08a150242019e166d12206b36022021-11-11T18:45:34ZMolecular Structure Effect of a Self-Assembled Monolayer on Thermal Resistance across an Interface10.3390/polym132137322073-4360https://doaj.org/article/f3e0b08a150242019e166d12206b36022021-10-01T00:00:00Zhttps://www.mdpi.com/2073-4360/13/21/3732https://doaj.org/toc/2073-4360Understanding heat transfer across an interface is essential to a variety of applications, including thermal energy storage systems. Recent studies have shown that introducing a self-assembled monolayer (SAM) can decrease thermal resistance between solid and fluid. However, the effects of the molecular structure of SAM on interfacial thermal resistance (ITR) are still unclear. Using the gold–SAM/PEG system as a model, we performed nonequilibrium molecular dynamics simulations to calculate the ITR between the PEG and gold. We found that increasing the SAM angle value from 100° to 150° could decrease ITR from 140.85 × 10<sup>−9</sup> to 113.79 × 10<sup>−9</sup> m<sup>2</sup> K/W owing to penetration of PEG into SAM chains, which promoted thermal transport across the interface. Moreover, a strong dependence of ITR on bond strength was also observed. When the SAM bond strength increased from 2 to 640 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">kcal</mi><mo mathvariant="normal">⋅</mo><msup><mrow><mi mathvariant="normal">mol</mi></mrow><mrow><mo mathvariant="normal">−</mo><mn mathvariant="normal">1</mn></mrow></msup><msup><mi mathvariant="sans-serif">Å</mi><mrow><mo mathvariant="normal">−</mo><mn mathvariant="normal">2</mn></mrow></msup></mrow></semantics></math></inline-formula>, ITR first decreased from 106.88 × 10<sup>−9</sup> to 102.69 × 10<sup>−9</sup> m<sup>2</sup> K/W and then increased to 123.02 × 10<sup>−9</sup> m<sup>2</sup> K/W until reaching a steady state. The minimum ITR was obtained when the bond strength of SAM was close to that of PEG melt. The matching vibrational spectra facilitated the thermal transport between SAM chains and PEG. This work provides helpful information regarding the optimized design of SAM to enhance interfacial thermal transport.Lijian SongYouchen ZhangWeimin YangJing TanLisheng ChengMDPI AGarticlemolecular dynamic simulationcoarse-grainedthermal resistanceself-assembled monolayerPEGOrganic chemistryQD241-441ENPolymers, Vol 13, Iss 3732, p 3732 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	molecular dynamic simulation coarse-grained thermal resistance self-assembled monolayer PEG Organic chemistry QD241-441
spellingShingle	molecular dynamic simulation coarse-grained thermal resistance self-assembled monolayer PEG Organic chemistry QD241-441 Lijian Song Youchen Zhang Weimin Yang Jing Tan Lisheng Cheng Molecular Structure Effect of a Self-Assembled Monolayer on Thermal Resistance across an Interface
description	Understanding heat transfer across an interface is essential to a variety of applications, including thermal energy storage systems. Recent studies have shown that introducing a self-assembled monolayer (SAM) can decrease thermal resistance between solid and fluid. However, the effects of the molecular structure of SAM on interfacial thermal resistance (ITR) are still unclear. Using the gold–SAM/PEG system as a model, we performed nonequilibrium molecular dynamics simulations to calculate the ITR between the PEG and gold. We found that increasing the SAM angle value from 100° to 150° could decrease ITR from 140.85 × 10<sup>−9</sup> to 113.79 × 10<sup>−9</sup> m<sup>2</sup> K/W owing to penetration of PEG into SAM chains, which promoted thermal transport across the interface. Moreover, a strong dependence of ITR on bond strength was also observed. When the SAM bond strength increased from 2 to 640 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">kcal</mi><mo mathvariant="normal">⋅</mo><msup><mrow><mi mathvariant="normal">mol</mi></mrow><mrow><mo mathvariant="normal">−</mo><mn mathvariant="normal">1</mn></mrow></msup><msup><mi mathvariant="sans-serif">Å</mi><mrow><mo mathvariant="normal">−</mo><mn mathvariant="normal">2</mn></mrow></msup></mrow></semantics></math></inline-formula>, ITR first decreased from 106.88 × 10<sup>−9</sup> to 102.69 × 10<sup>−9</sup> m<sup>2</sup> K/W and then increased to 123.02 × 10<sup>−9</sup> m<sup>2</sup> K/W until reaching a steady state. The minimum ITR was obtained when the bond strength of SAM was close to that of PEG melt. The matching vibrational spectra facilitated the thermal transport between SAM chains and PEG. This work provides helpful information regarding the optimized design of SAM to enhance interfacial thermal transport.
format	article
author	Lijian Song Youchen Zhang Weimin Yang Jing Tan Lisheng Cheng
author_facet	Lijian Song Youchen Zhang Weimin Yang Jing Tan Lisheng Cheng
author_sort	Lijian Song
title	Molecular Structure Effect of a Self-Assembled Monolayer on Thermal Resistance across an Interface
title_short	Molecular Structure Effect of a Self-Assembled Monolayer on Thermal Resistance across an Interface
title_full	Molecular Structure Effect of a Self-Assembled Monolayer on Thermal Resistance across an Interface
title_fullStr	Molecular Structure Effect of a Self-Assembled Monolayer on Thermal Resistance across an Interface
title_full_unstemmed	Molecular Structure Effect of a Self-Assembled Monolayer on Thermal Resistance across an Interface
title_sort	molecular structure effect of a self-assembled monolayer on thermal resistance across an interface
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/f3e0b08a150242019e166d12206b3602
work_keys_str_mv	AT lijiansong molecularstructureeffectofaselfassembledmonolayeronthermalresistanceacrossaninterface AT youchenzhang molecularstructureeffectofaselfassembledmonolayeronthermalresistanceacrossaninterface AT weiminyang molecularstructureeffectofaselfassembledmonolayeronthermalresistanceacrossaninterface AT jingtan molecularstructureeffectofaselfassembledmonolayeronthermalresistanceacrossaninterface AT lishengcheng molecularstructureeffectofaselfassembledmonolayeronthermalresistanceacrossaninterface
_version_	1718431740320546816

Molecular Structure Effect of a Self-Assembled Monolayer on Thermal Resistance across an Interface

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