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 297.7oC, 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297.7oC，高于本征导热LC-PI膜（2.1 GPa和262.4oC）和相同CNT用量下CNT/LC-PI导热复合膜（2.2 GPa和291.3oC）。