Kunpeng Ruan#, Xuetao Shi#, Yali Zhang, Yongqiang Guo*, Xiao Zhong and Junwei Gu*. Electric-Field-Induced Alignment of Functionalized Carbon Nanotubes Inside Thermally Conductive Liquid Crystalline Polyimide Composite Films. Angewandte Chemie International Edition, 2023, 10.1002/anie.202309010. 2022IF=16.6.（1区化学Top期刊）

https://doi.org/10.1002/anie.202309010

Abstract

The positive liquid crystals, 4''-heptyl-4-biphenylcarbonitrile (7CB), are used to functionalize carbon nanotubes (LC-CNT), which can be aligned in the liquid crystalline polyimide (LC-PI) matrix under an alternating electric field to fabricate the thermally conductive LC-CNT/LC-PI composite films. The efficient establishment of thermal conduction pathways in thermally conductive LC-CNT/LC-PI composite films with a low amount of LC-CNT is achieved through the oriented alignment of LC-CNT within the LC-PI matrix. When the mass fraction of LC-CNT is 15 wt%, the in-plane thermal conductivity coefficient (λ∥) and the through-plane thermal conductivity coefficient (λ⊥) of the LC-CNT/LC-PI composite films reach 4.02 W/(m·K) and 0.55 W/(m·K), which are 90.5% and 71.9% higher than those of the intrinsically thermally conductive LC-PI films respectively, also 28.8% and 5.8% higher than those of the CNT/LC-PI composite films respectively. Meanwhile, the thermally conductive LC-CNT/LC-PI composite films also possess excellent mechanical and heat resistance properties. The Young''s modulus and the heat resistance index are 2.3 GPa and 297.7^oC, respectively, which are higher than the intrinsically thermally conductive LC-PI films and the thermally conductive CNT/LC-PI composite films under the same amount of CNT.

采用正性液晶分子4-氰基-4''-庚基联苯（7CB）对碳纳米管（CNT）进行表面功能化改性（LC-CNT），进而在交流电场作用下与本征导热液晶聚酰亚胺（LC-PI）基体复合制备LC-CNT/LC-PI导热复合膜。LC-CNT在LC-PI基体中的定向排列实现了低LC-CNT用量下LC-CNT/LC-PI导热复合膜中导热通路的高效构筑。当LC-CNT质量分数为15 wt%时，LC-CNT/LC-PI导热复合膜室温下的面内导热系数（λ∥）和面间导热系数（λ⊥）分别达到4.02 W/(m·K)和0.55 W/(m·K)，较本征导热LC-PI膜的λ∥（2.11 W/(m·K)）和λ⊥（0.32 W/(m·K)）提升了90.5%和71.9%，也明显高于相同CNT用量下CNT/LC-PI导热复合膜（λ∥=3.12 W/(m·K)，λ⊥=0.52 W/(m·K)）。此时，LC-CNT/LC-PI导热复合膜还兼具优异的力学性能和耐热性能，杨氏模量和耐热指数分别为2.3 GPa和297.7^oC，高于本征导热LC-PI膜（2.1 GPa和262.4^oC）和相同CNT用量下CNT/LC-PI导热复合膜（2.2 GPa和291.3^oC）。

论文亮点

1. 采用正性液晶分子4-氰基-4’-庚基联苯对CNT表面功能化改性制得LC-CNT，施加交流电场可以实现LC-CNT的定向排列。

2. LC-CNT导热填料的定向排列实现了低LC-CNT用量下LC-CNT/LC-PI导热复合膜中导热通路的高效构筑。15 wt% LC-CNT/LC-PI导热复合膜室温下的λ∥和λ⊥分别达到4.02 W/(m·K)和0.55 W/(m·K)。

3. LC-CNT/LC-PI导热复合膜还兼具优异的力学性能和耐热性能，15 wt% LC-CNT/LC-PI导热复合膜的杨氏模量、拉伸强度和耐热指数分别达到2.3 GPa、70.0 MPa和297.7^oC。

第一作者：阮坤鹏 & 史学涛

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