Hao Jiang, Yuhui Xie, Mukun He, Jindao Li, Feng Wu, Hua Guo, Yongqiang Guo, Delong Xie*, Yi Mei and Junwei Gu*. Highly Thermally Conductive and Flame-Retardant Waterborne Polyurethane Composites with 3D BNNS Bridging Structures via Magnetic Field Assistance. Nano-Micro Letters, 2025, 17: 138. 2023IF=31.6.（1区材料科学Top期刊）

https://doi.org/10.1007/s40820-025-01651-1

Abstract

The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in modern electronic devices. Hence, a composite with three-dimensional network (Ho/U-BNNS/WPU) is developed by simultaneously incorporating magnetically modified boron nitride nanosheets (M@BNNS) and non-magnetic organo-grafted BNNS (U-BNNS) into waterborne polyurethane (WPU) to synchronous molding under a horizontal magnetic field. The results indicate that the continuous in-plane pathways formed by M@BNNS aligned along the magnetic field direction, combined with the bridging structure established by U-BNNS, enable Ho/U-BNNS/WPU to exhibit exceptional in-plane (λ//) and through-plane thermal conductivities (λ⊥). In particular, with the addition of 30 wt% M@BNNS and 5 wt% U-BNNS, the λ// and λ⊥ of composites reach 11.47 and 2.88 W/(m·K) respectively, which representing a 194.2% improvement in λ⊥ compared to the composites with a single orientation of M@BNNS. Meanwhile, Ho/U-BNNS/WPU exhibits distinguished thermal management capabilities as thermal interface materials for LED and chips. The composites also demonstrate excellent flame retardancy, with a peak heat release and total heat release reduced by 58.9% and 36.9% respectively, compared to WPU. Thus, this work offers new insights into the thermally conductive structural design and efficient flame-retardant systems of polymer composites, presenting broad application potential in electronic packaging fields.

在聚合物电气封装材料中，优化热传导通路的微观结构设计对于满足现代电子设备对高效散热管理和热失控安全至关重要。因此，本研究开发了一种具有三维导热网络的复合材料（Ho/U-BNNS/WPU），通过同时引入磁性改性氮化硼纳米片（M@BNNS）和非磁性有机接枝氮化硼纳米片（U-BNNS）至水性聚氨酯（WPU）中，并在水平磁场下同步成型。研究结果表明，由M@BNNS沿磁场方向排列形成的连续面内导热通路，以及U-BNNS所构建的桥接结构，使Ho/U-BNNS/WPU复合材料表现出优异的面内（λ//）和面间（λ⊥）导热性能。尤其是当M@BNNS和U-BNNS的添加量分别为30 wt%和5 wt%时，复合材料的λ//和λ⊥分别达到11.47 W/(m·K)和2.88 W/(m·K)，其中λ⊥较单一取向M@BNNS复合材料提升了194.2%。此外，Ho/U-BNNS/WPU作为LED和芯片的热界面材料展现出卓越的热管理能力。同时，该复合材料还表现出优异的阻燃性能，其峰值热释放速率和总热释放量相较于纯WPU分别降低了58.9%和36.9%。因此，本研究为聚合物复合材料的导热结构设计及高效阻燃体系提供了新思路，并在电子封装领域展现出广阔的应用前景。

论文亮点

1. 通过在聚合物基体中同时引入磁性填料改性的氮化硼纳米片（M@BNNS）和非磁性填料U-BNNS，并在水平磁场下同步成型，成功制备出具有三维热传导通路的复合材料。

2. 得益于三维桥接结构的微观设计，仅添加5 wt%的U-BNNS，复合材料的面间导热系数（λ⊥）便达到2.88 W/(m·K)，相较于单一取向的复合材料提升了194.2%。

3. 三维桥接结构的复合材料还表现出优异的阻燃性能，这主要归因于凝聚相和气相的协同阻燃机制，有效降低了电子设备发生热失控的风险。

第一作者：姜豪

邮件地址：jianghao0820@mail.nwpu.edu.cn

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