Modulation of Interfacial Thermal Transport between Fumed Silica Nanoparticles by Surface Chemical Functionalization for Advanced Thermal Insulation

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Takashi Kodama
  • Nobuhiro Shinohara
  • Shih-Wei Hung
  • Bin Xu
  • Masanao Obori
  • And 2 others
  • Donguk Suh
  • Junichiro Shiomi

Detail(s)

Original languageEnglish
Pages (from-to)17404–17411
Journal / PublicationACS Applied Materials and Interfaces
Volume13
Issue number15
Online published12 Apr 2021
Publication statusPublished - 21 Apr 2021

Abstract

Since solid-state heat transport in a highly porous nanocomposite strongly depends on the thermal boundary conductance (TBC) between constituent nanomaterials, further suppression of the TBC is important for improving performance of thermal insulators. Here, targeting a nanocomposite fabricated by stamping fumed silica nanoparticles, we perform a wide variety of surface functionalizations on fumed silica nanoparticles by a silane coupling method and investigate the impact on the thermal conductivity (Km). The Km of the silica nanocomposite is approximately 20 and 9 mW/m/K under atmospheric and vacuum conditions at the material density of 0.2 g/cm3 without surface functionalization, respectively, and the experimental results indicate that the Kcan be modulated depending on the chemical structure of molecules. The surface modification with a linear alkyl chain of optimal length significantly suppresses Km by approximately 30%, and the suppression can be further enhanced to approximately 50% with an infrared opacifier. The magnitude of suppression was found to sensitively depend on the length of the terminal chain. The magnitude is also related to the number of reactive silanol groups in the chemical structure, where the surface modification with fluorocarbon gives the largest suppression. The surface hydrophobization merits thermal insulation through significant suppression of the TBC, presumably by reducing the water molecules that otherwise would serve as heat conduction channels at the interface. On the other hand, when the chain length is long, the suppression is counteracted by the enhanced phonon transmission through the silane coupling molecules that grow with the chain length. This is supported by the analytical model and present simulation results, leading to prediction of the optimal chemical structure for better thermal insulation.

Research Area(s)

  • interfacial heat transport, porous material, silane coupling, silica nanocomposite, thermal boundary conductance, thermal insulator, vacuum-insulated panel

Citation Format(s)

Modulation of Interfacial Thermal Transport between Fumed Silica Nanoparticles by Surface Chemical Functionalization for Advanced Thermal Insulation. / Kodama, Takashi; Shinohara, Nobuhiro; Hung, Shih-Wei; Xu, Bin; Obori, Masanao; Suh, Donguk; Shiomi, Junichiro.

In: ACS Applied Materials and Interfaces, Vol. 13, No. 15, 21.04.2021, p. 17404–17411.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review