Cross-Plane and In-Plane Heat Conductions in Layer-by-Layer Membrane: Molecular Dynamics Study

Kawagoe, Yoshiaki; Surblys, Donatas; Matsubara, Hiroki; Kikugawa, Gota; Ohara, Taku

doi:10.1021/acs.langmuir.0c00845

Cited by 22 publications

(12 citation statements)

References 78 publications

(135 reference statements)

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“…By attracting atoms closer to each other, Coulomb interaction rises the repulsive vdW interaction, which enhances the thermal conductivity. This mechanism has also been discussed in previous works. − So, it appears that hydrogen bonds, to which Coulomb interaction dominantly contributes, are essential to determine the adsorption structure of alcohol, which enables more favorable energy transfer.…”

Section: Results and Discussionsupporting

confidence: 53%

Molecular Dynamics Study on the Effect of Long-Chain Surfactant Adsorption on Interfacial Heat Transfer between a Polymer Liquid and Silica Surface

et al. 2020

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The addition of surfactants to polymer-based thermal interface materials applied to improve the heat dissipation efficiency of chip surfaces in contact has attracted attention for the microelectronic processing technology. In the present study, the mechanism by which a long-chain surfactant affects heat transfer across the interface between solid surface and polymer liquid was investigated by non-equilibrium molecular dynamics simulation. We constructed a system where tetracosane was used as a solvent and contained alcohol molecules as a surfactant, and they were placed between two flat silica surfaces under a thermal gradient. The effect of the hydrophilicity of silica surface, the concentration of the surfactant, and chain length of the surfactant on silica–liquid interfacial thermal resistance R b were examined. Alcohol surfactant molecules preferred to adsorb onto the hydrophilic silica (Si–OH) surface due to hydrogen bonding between alcohol and silanol hydroxyl groups. It was found that R b reduced not only with the adsorption amount of alcohol molecules but also with the chain length of alcohol. The van der Waals interaction contribution was dominant for solid–liquid and liquid–liquid heat conduction near the interface. The hydroxyl terminals of alcohol molecules were vertically adsorbed onto the Si–OH surface due to hydrogen bonds, which produced a heat path from silanols to the hydroxyl groups of alcohol. Furthermore, heat was also exchanged between alcohol hydroxyl and alkyl groups via intramolecular interaction and between the alcohol alkyl groups and nearby solvent molecules via van der Waals (vdW) intermolecular interaction. This resulted in an efficient heat path from solid surface silanols to liquid bulk. As the alcohol chain length increased without changing the number of adsorbed alcohol molecules, the heat transfer through this heat path increased, which led to a decrease in R b. These results provided insight toward the guiding principle for the molecular design of complex surfactants to enhance the interfacial heat transfer.

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Section: Results and Discussionsupporting

confidence: 53%

Molecular Dynamics Study on the Effect of Long-Chain Surfactant Adsorption on Interfacial Heat Transfer between a Polymer Liquid and Silica Surface

et al. 2020

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“…From the force field energy function according to Equation ( 7), E angle and E bond tend to occupy a significant proportion of all function items and are demonstrated to be substantial in polymer thermal transport [36]. Hence, we focused on two main structural factors: SAM equilibrium angle of backbone θ eq and bond stretching K b defined in Formulas (8) and (9). The θ eq angle was among three SNO beads.…”

Section: Resultsmentioning

confidence: 99%

“…Most recently, several types of SAMs have been proposed to improve thermal conductance. These SAMs include: cetyltrimethylammonium bromide (CTAB) and polyethylene glycol (PEG) grafted on a Au surface [5,6], poly (acrylic acid) (PAA), polyacrylamide (PAM), polyvinyl alcohol (PVA),poly (acrylic acid)/polyethyleneimine (PAA/PEI) SAMs layer-by-layer-anchored on lithium cobalt oxide [7], and phosphonate-functionalized azastibazolium π-electron (PAE) SAMs on Pt electrodes [8].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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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 × 10−9 to 113.79 × 10−9 m2 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 kcal⋅mol−1Å−2, ITR first decreased from 106.88 × 10−9 to 102.69 × 10−9 m2 K/W and then increased to 123.02 × 10−9 m2 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.

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“…In the reactions between DGEBA and DDS, both epoxy‐primary and epoxy‐secondary amines as well as epoxy‐hydroxyl group reaction, hereinafter etherification, which is the reaction between the hydroxyl groups (generated by the epoxy‐primary amine reactions) and the epoxy group were considered. Since a detailed explanation of the curing simulation method has been provided in a previous report, 29 the algorithm and a brief explanation of the simulation procedure 25,30,31,32,33,34,35,36 are described in Figure 3 and the Figure S1, respectively. The reaction probability p was calculated using the Arrhenius equation (Equation ).

p = A \exp ((), - \frac{E_{a}}{RT})

where E a is the activation energy, R is the gas constant, and T is the local temperature around the reactive sites.…”

Section: Curing Simulationmentioning

confidence: 99%

“…Curing reactions of (b) epoxy and primary amine, (c) epoxy and secondary amine, and (d) epoxy and hydroxyl group. The molecular visualizations were produced by the VMD package, 41 previous report, 29 the algorithm and a brief explanation of the simulation procedure 25,30,31,32,33,34,35,36 are described in Figure 3 and the Figure S1, respectively. The reaction probability p was calculated using the Arrhenius equation Equation 1.…”

Section: Molecular Dynamics Simulations For Exothermic Reaction Systemmentioning

confidence: 99%

Amine/epoxy stoichiometric ratio dependence of crosslinked structure and ductility inamine‐curedepoxy thermosetting resins

Odagiri

Shirasu

Kawagoe

et al. 2021

J of Applied Polymer Sci

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Epoxy‐amine thermosetting resins undergo different reactions depending on the amine/epoxy stoichiometric ratio (r). Although many desirable properties can be achieved by varying the stoichiometric ratio, the effects of the variation on the crosslinked structure and mechanical properties and the contribution of these factors to the ductility of materials have not been fully elucidated. This study investigates the brittle‐ductile behavior of epoxies with various stoichiometric ratios and performs curing simulations using molecular dynamics (MD) to evaluate the crosslinked structures. The molecular structure is predominantly branched in low‐stoichiometric ratio samples, whereas the chain extension type structure dominates the high‐stoichiometric ratio samples. As a result, the higher‐stoichiometric ratio samples enhances the ductility of materials and the elongation at break increases form 1.4% (r = 0.6) to 11.4% (r = 1.4). Additionally, the tensile strength (105.4 MPa) and strain energy (7.96 J/cm3) are maximum at r = 0.8 and 1.2, respectively. On the other hand, the Young's modulus is negatively impacted and it decreased from 4.2 to 2.7 GPa with increasing stoichiometric ratio.

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Cross-Plane and In-Plane Heat Conductions in Layer-by-Layer Membrane: Molecular Dynamics Study

Cited by 22 publications

References 78 publications

Molecular Dynamics Study on the Effect of Long-Chain Surfactant Adsorption on Interfacial Heat Transfer between a Polymer Liquid and Silica Surface

Molecular Dynamics Study on the Effect of Long-Chain Surfactant Adsorption on Interfacial Heat Transfer between a Polymer Liquid and Silica Surface

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

Amine/epoxy stoichiometric ratio dependence of crosslinked structure and ductility inamine‐curedepoxy thermosetting resins

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