Ordered Alignment of Liquid Crystalline Graphene Fluoride for Significantly Enhancing Thermal Conductivities of Liquid Crystalline Polyimide Composite Films

• Published in: Macromolecules Vol. 55; no. 10; pp. 4134 - 4145
• Main Authors: Ruan, Kunpeng, Gu, Junwei
• Format: Journal Article
• Language: English
• Published: American Chemical Society 24.05.2022
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/acs.macromol.2c00491

The low thermal conductivity coefficient (λ) of polyimide (PI) films are limiting their application in high-power electronic equipment, 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.