High Thermally Conducting Polymer-based Films with Magnetic Field

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Applications of Polymer, Composite, and Coating Materials

High Thermally Conducting Polymer-based Films with Magnetic Field-assisted Vertically Aligned Hexagonal Boron Nitride for Flexible Electronic Encapsulation Jie Yuan, Xitang Qian, ZhiChao Meng, Bo Yang, and Zhi-Quan Liu ACS Appl. Mater. Interfaces, Just Accepted Manuscript • Publication Date (Web): 26 Apr 2019 Downloaded from http://pubs.acs.org on April 26, 2019

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ACS Applied Materials & Interfaces

High Thermally Conducting Polymer-based Films with Magnetic Field-assisted Vertically Aligned Hexagonal Boron Nitride for Flexible Electronic Encapsulation Jie Yuan1,2,, Xitang Qian1,2,, Zhichao Meng1,2, Bo Yang4, Zhi-Quan Liu1,2,3* 1Institute 2School

of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China

of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China

3Shenzhen 4Key

Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China

Laboratory for Anisotropy and Texture of Materials, Ministry of Education, School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China

#These

authors contributed equally to this work.

Abstract Here, a facile, low-cost and high efficiency method to construct vertically aligned hexagonal boron nitride nanosheets (BNNs) thermal conduction channels structure is proposed to improve the thermal conductivity. First, exfoliated negatively charged BNNs and positively charged FeCo nanocubes self-assemble to form complex nanomaterials by strong electrostatic interactions. Then the BNNs can orient with FeCo nanocubes in magnetic field, and the {001} facets of BNNs adsorb on the {100} facets of FeCo nanocubes. The large scale range and high-density FeCo/hBN aligned structures are observed by SEM, which can act as thermal dissipation channels by conveying more phonons through a preponderant thermally conductive direction. The thermal conductivity of the composite films with 30 wt% FeCo and 50 wt% BN filler is 2.25 W m-1 K-1, 7 times higher than that of the films only containing 50 wt% randomly distributed hBN filler (0.325 W m-1 K-1), and 20 times higher than pure PDMS films (0.114 W m-1 K-1). The thermal management capability of the composite films is evaluated as a thermal conducting substrate of LED chip and the infrared thermal technology. Apart from the surprising thermal conductivity, FeCo-BNNs composite films also exhibit superb flexibility.

Keywords: hexagonal boron nitride nanosheets(BNNs), magnetic FeCo nanocubes, electrostatic interactions, vertically orientation, thermal conductivity

*Corresponding

author: Zhi-Quan Liu, Professor, E-mail:[email protected] 1

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1. Introduction With the rapid development of the very-large-scale integration and the increase of high power device, one of the most challenges in three-dimensional (3D) integration is the heat management which is a vital problem that needs to be dealt urgently to facilitate the heat dissipation and relieve the thermal stress.1,2 For the next-generation electronics, flexible microelectronics are also faced with the heat dissipation problems.3 Over the last few decades, polymers have gained the attention as packaging or substrate materials because of their light weight, flexibly processability and low cost.4-6 However, these polymers have obvious drawback which limited their application, such as low thermal conductivity(TC,