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區化學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''-庚基聯苯（7CB）對碳納米管（CNT）進行表面功能化改性（LC-CNT），進而在交流電場作用下與本征導熱液晶聚酰亞胺（LC-PI）基體復合制備LC-CNT/LC-PI導熱復合膜。LC-CNT在LC-PI基體中的定向排列實現了低LC-CNT用量下LC-CNT/LC-PI導熱復合膜中導熱通路的高效構筑。當LC-CNT質量分數為15 wt%時，LC-CNT/LC-PI導熱復合膜室溫下的面內導熱系數（λ∥）和面間導熱系數（λ⊥）分別達到4.02 W/(m·K)和0.55 W/(m·K)，較本征導熱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%，也明顯高于相同CNT用量下CNT/LC-PI導熱復合膜（λ∥=3.12 W/(m·K)，λ⊥=0.52 W/(m·K)）。此時，LC-CNT/LC-PI導熱復合膜還兼具優異的力學性能和耐熱性能，楊氏模量和耐熱指數分別為2.3 GPa和297.7oC，高于本征導熱LC-PI膜（2.1 GPa和262.4oC）和相同CNT用量下CNT/LC-PI導熱復合膜（2.2 GPa和291.3oC）。
論文亮點
1. 采用正性液晶分子4-氰基-4’-庚基聯苯對CNT表面功能化改性制得LC-CNT，施加交流電場可以實現LC-CNT的定向排列。
2. LC-CNT導熱填料的定向排列實現了低LC-CNT用量下LC-CNT/LC-PI導熱復合膜中導熱通路的高效構筑。15 wt% LC-CNT/LC-PI導熱復合膜室溫下的λ∥和λ⊥分別達到4.02 W/(m·K)和0.55 W/(m·K)。
3. LC-CNT/LC-PI導熱復合膜還兼具優異的力學性能和耐熱性能，15 wt% LC-CNT/LC-PI導熱復合膜的楊氏模量、拉伸強度和耐熱指數分別達到2.3 GPa、70.0 MPa和297.7oC。
第一作者：阮坤鵬 & 史學濤
郵箱：[email protected] & [email protected]