Enhanced Thermal Conductivity of Polyimide Composites with Boron Nitride Nanosheets

Ting Wang,Yapeng Chen,Shuangyi Li,Ruiyang Kang,Mengjie Wang,Zehui Duan,Yuming Wu,Xiao Hou,Li Fu,Jinhong Yu,Nan Jiang,Liangchao Guo

doi:10.1038/s41598-018-19945-3

Abstract

A strategy was reported to prepare boron nitride nanosheets (BNNSs) by a molten hydroxide assisted liquid exfoliation from hexagonal boron nitride (h-BN) powder. BNNSs with an average thickness of 3 nm were obtained by a facile, low-cost, and scalable exfoliation method. Highly thermally conductive polyimide (PI) composite films with BNNSs filler were prepared by solution-casting process. The in-plane thermal conductivity of PI composite films with 7 wt% BNNSs is up to 2.95 W/mK, which increased by 1,080% compared to the neat PI. In contrast, the out-of plane thermal conductivity of the composites is 0.44 W/mK, with an increase by only 76%. The high anisotropy of thermal conductivity was verified to be due to the high alignment of the BNNSs. The PI/BNNSs composite films are attractive for the thermal management applications in the field of next-generation electronic devices.

Highlights

The carbon and metal materials are highly electrically conductive and small additions of these fillers into polymers result in high electrical conductivity of the composites, which restricts the application
The results indicate that the molten hydroxide treatment of BN powder could significantly improve the yield of boron nitride nanosheets (BNNSs) in the liquid exfoliation stage
We found that the out-of plane thermal conductivity of PI composite films with 7 wt% BNNSs fillers is 0.44 W/mK, which gives a slight improvement (76%), compared to that of neat PI (0.25 W/mK)

Summary

Introduction

The carbon and metal materials are highly electrically conductive and small additions of these fillers into polymers result in high electrical conductivity of the composites, which restricts the application. As the low aspect ratio of h-BN filler, conventional PI composite achieve the thermal conductivity of 1–5 W/mK by utilizing large loading volume fraction h-BN filler (of up to ~50%). Large aspect ratio boron nitride nanosheets (BNNSs) exhibit many potential applications including ultraviolet light emitter, field emitters, and a superior substrate for graphene-based electrical devices[23,24,25,26,27,28] and a superior thermal conductivity ranges from 1,700–2,000 W/mK29. Many efforts have been used to prepare BNNSs including micromechanical cleavage[31], ultrasonication[32], and high energy electron beam irradiation[33], chemical vapor deposition[34], and liquid exfoliation[35]. BNNSs still suffer from a low cost, high yield, and facile exfoliation method. The composites are promising for using as a heat dissipation material in next-generation electronic device

Methods

Results

Conclusion