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SFPC课题组导热高分子复合材料工作发表在Macromolecules上


Kunpeng Ruan and Junwei Gu*. Ordered Alignment of Liquid Crystalline Graphene Fluoride for Significantly Enhancing Thermal Conductivities of Liquid Crystalline Polyimide Composite Films. Macromolecules, 2022, 10.1021/acs.macromol.2c00491. 2020IF=5.985.1区化学Top期刊)

https://doi.org/10.1021/acs.macromol.2c00491

Abstract

Low thermal conductivity coefficient (λ) of polyimide (PI) films are limiting their application in high-power electronic equipments, and the disordered alignment of fillers discourage efficient improvement of λ for PI-based composite films. Herein, polyethylene glycol trimethylnonyl ether is used to perform liquid crystalline modification on graphene fluoride (LC-GeF) to achieve ordered alignment. Intrinsically thermally conductive liquid crystalline PI (LC-PI) matrix is utilized to fabricate thermally conductive LC-GeF/LC-PI composite films. In-plane λ (λ) and through-plane λ (λ) of 15 wt% LC-GeF/LC-PI composite films reach 4.21 and 0.63 W/(m·K), 446.8% and 320.0% higher than λ (0.77 W/(m·K)) and λ (0.15 W/(m·K)) of normal PI films, 99.5% and 96.9% higher than λ (2.11 W/(m·K)) and λ (0.32 W/(m·K)) of LC-PI films, also higher than 15 wt% GeF/LC-PI composite films. Additionally, LC-GeF/LC-PI composite films possess more excellent insulating, mechanical and thermal properties than GeF/LC-PI composite films.

聚酰亚胺(PI)膜较低的本征导热系数(λ)限制了其在高功率电子设备中的应用。常规PI基导热复合膜中的导热填料往往无序排列,阻碍了λ的高效提升。本文采用聚乙二醇三甲基壬基醚(TMN)对溶剂插层-超声剥离法制备的氟化石墨烯(GeF)进行液晶化改性(LC-GeF),再与本征导热液晶PILC-PI)基体复合制备LC-GeF/LC-PI导热复合膜。当LC-GeF导热填料的质量分数为15 wt%时,LC-GeF/LC-PI导热复合膜室温下的面内λλ)和面间λλ)分别达到4.21 W/(m·K)0.63 W/(m·K),较普通PI膜的λ0.77 W/(m·K))和λ0.15 W/(m·K))提升了446.8%320.0%,较本征导热LC-PI膜的λ2.11 W/(m·K))和λ0.32 W/(m·K))提升了99.5%96.9%,也高于相同填料用量下GeF/LC-PI导热复合膜。此外,相同填料用量下,LC-GeF/LC-PI复合膜还具有较GeF/LC-PI复合膜更加优异的绝缘性能、力学性能和热性能。

本文亮点

1. 利用非离子型表面活性剂TMNGeF进行液晶化改性,基于TMNGeF间氢键作用实现了LC-GeF导热填料的微观有序排列。

2. LC-GeF导热填料的质量分数为15 wt%时,LC-GeF/LC-PI导热复合膜室温下的λλ分别达到4.21 W/(m·K)0.63 W/(m·K),较普通PI膜的λ0.77 W/(m·K))和λ0.15 W/(m·K))提升了446.8%320.0%

3. LC-GeF/LC-PI导热复合膜具有优异的绝缘性能、力学性能和热性能,15 wt% LC-GeF/LC-PI导热复合膜的体积电阻率、杨氏模量、玻璃化转变温度和耐热指数分别为7.9×1014 Ω·cm2.4 GPa349.2oC278.7oC,明显优于普通PI膜(1.4×1013 Ω·cm1.4 GPa332.8oC266.6oC)。