writer：Kunpeng Ruan, Mukun Li, Yuheng Pang, Mukun He, Hua Guo*, Xuetao Shi and Junwei Gu*
keywords：Hetero-structured thermally conductive fillers, Intrinsically thermally conductive liquid crystalline polyimide, Liquid crystalline functionalization, Thermally conductive composite films
source：期刊
Issue time：2025年

Kunpeng Ruan, Mukun Li, Yuheng Pang, Mukun He, Hua Guo*, Xuetao Shi and Junwei Gu*. Molecular Brush-Grafted Liquid Crystalline Hetero-Structured Fillers for Boosting Thermal Conductivity of Polyimide Composite Films. Advanced Functional Materials, 2025, 10.1002/adfm.202506563. 2023IF=18.5.（1区材料科学Top期刊）

https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202506563

Abstract

Hetero-structured thermally conductive fillers, benefiting from the low interfacial thermal resistance and fillers’ synergistic effect, have been proven to be the ideal choice for improving the thermal conductivities of polymer composites. However, hetero-structured fillers are usually disorderly distributed in the polymer matrix, hindering the further improvement of the efficiency of constructing thermal conduction pathways in polymer composites. This work proposes the new strategy to graft polymethyl methacrylate molecular brushes on the surfaces of fluorinated graphene@carbon nanotube (FG@CNT) hetero-structured thermally conductive fillers by atom transfer radical polymerization. FG@CNT is orderly arranged and present the liquid crystalline state (LC-(FG@CNT), which are then introduced into the liquid crystalline polyimide (LC-PI) matrix with high intrinsic thermally conductivity to fabricate LC-(FG@CNT)/LC-PI thermally conductive composite films. The in-plane and through-plane thermal conductivities (λ_∥, λ_⊥) of 15 wt% LC-(FG@CNT)/LC-PI films reach 5.66 and 0.76 W·m^-1·K^-1, respectively, which are 168.2% and 137.5% higher than those of the LC-PI films (λ_∥=2.11 W·m^-1·K^-1, λ_⊥=0.32 W·m^-1·K^-1), also significantly higher than those of 15 wt% FG@CNT/LC-PI composite films (λ_∥=4.72 W·m^-1·K^-1, λ_⊥=0.74 W·m^-1·K^-1). Demonstrated by heat dissipation testing and finite element simulation, the LC-(FG@CNT)/LC-PI composite films show excellent thermal management capabilities and great application potential in the new generation of flexible electronic devices.

异质结构导热填料受益于低界面热障和填料协同效应，已被证明是提升高分子复合材料导热性能的理想选择，但其往往在高分子基体内无序分布，影响高分子复合材料内导热通路构筑效率的进一步提升。本文提出通过原子转移自由基聚合在氟化石墨烯@碳纳米管（GeF@CNT）异质结构导热填料表面接枝聚甲基丙烯酸甲酯分子刷的新策略，使GeF@CNT有序排列并呈液晶态（LC-(GeF@CNT)），并将其引入本征高导热液晶聚酰亚胺（LC-PI）基体中制备LC-(GeF@CNT)/LC-PI导热复合膜。当LC-(GeF@CNT)的质量分数为15 wt%时，LC-(GeF@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5.66 W·m^-1·K^-1和0.76 W·m^-1·K^-1，较本征导热LC-PI膜的λ_∥（2.11 W·m^-1·K^-1）和λ_⊥（0.32 W·m^-1·K^-1）提升了168.2%和137.5%，也明显高于相同GeF@CNT用量下GeF@CNT/LC-PI导热复合膜（λ_∥=4.72 W·m^-1·K^-1，λ_⊥=0.74 W·m^-1·K^-1）。经实际散热测试和有限元模拟，LC-(GeF@CNT)/LC-PI导热复合膜展现出优异的热管理能力，在新一代柔性电子设备中具备强大的应用潜力。