Mukun He, Xiao Zhong, Xinghan Lu, Jinwen Hu, Kunpeng Ruan, Hua Guo, Yali Zhang, Yongqiang Guo* and Junwei Gu*. Excellent Low-frequency Microwave Absorption and High Thermal Conductivity in Polydimethylsiloxane Composites Endowed by Hydrangea-like CoNi@BN Heterostructure Fillers. Advanced Materials, 2024, 36: 2410186. 2023IF=27.4

https://doi.org/10.1002/adma.202410186

Abstract

The advancement of thin, lightweight, and high-power electronic devices has increasingly exacerbated issues related to electromagnetic interference and heat accumulation. To address these challenges, we employed a spray-drying-sintering process to assemble chain-like CoNi and flake boron nitride (BN) into hydrangea-like CoNi@BN heterostructure fillers. These fillers were then composited with polydimethylsiloxane (PDMS) to develop CoNi@BN/PDMS composites, which integrate low-frequency microwave absorption and thermal conductivity. When the volume fraction of CoNi@BN is 44 vol% and the mass ratio of CoNi to BN is 3:1, the CoNi@BN/PDMS composites exhibit optimal performance in both low-frequency microwave absorption and thermal conductivity. These composites achieve a minimum reflection loss of -49.9 dB and a low-frequency effective absorption bandwidth of 2.40 GHz (3.92~6.32 GHz) at a thickness of 4.4 mm, fully covering the n79 band (4.4~5.0 GHz) for 5G communications. Meanwhile, the in-plane thermal conductivity (λ∥) of the CoNi@BN/PDMS composites is 7.31 W m^-1 K^-1, which is about 11.4 times of the λ∥ (0.64 W m^-1 K^-1) for pure PDMS, and 32% higher than that of the (CoNi/BN)/PDMS composites (5.52 W m^-1 K^-1) with the same volume fraction of CoNi and BN obtained through direct mixing.

电子设备的轻薄化和高功率化发展，导致其电磁干扰和热量聚集问题愈发严重。本文采用“喷雾干燥-烧结”工艺将链状CoNi和片状BN组装为绣球花状CoNi@BN异质结构填料，再将其与聚二甲基硅氧烷（PDMS）复合制备低频吸波/导热一体化CoNi@BN/PDMS复合材料。当CoNi@BN的体积分数为44 vol%且CoNi与BN质量比为3:1时，CoNi@BN/PDMS复合材料兼具最优的低频吸波性能和导热系数，厚度为4.4 mm时最小反射损耗（RLmin）为-49.9 dB、低频有效吸收带宽（EAB）为2.40 GHz（3.92~6.32 GHz），完全覆盖5G通讯涉及的n79（4.4~5.0 GHz）频段，其面内导热系数（λ∥）为7.31 W m^-1 K^-1，约为纯PDMS的λ∥（0.64 W m^-1 K^-1）的11.4倍，较相同CoNi和BN体积分数且直接共混的(CoNi/BN)/PDMS复合材料的λ∥（5.52 W m^-1 K^-1）提高了32%。

论文亮点

1. 采用“喷雾干燥-烧结”工艺将一维链状CoNi和二维片状BN组装成绣球花状CoNi@BN异质结构填料。当CoNi与BN质量比为3:1时，CoNi@BN具有优异的阻抗匹配和低频吸波性能。

2. 当CoNi@BN的体积分数为44 vol%时，4.4 mm的CoNi@BN/PDMS复合材料RLmin为-49.9 dB、低频EAB为2.40 GHz（3.92~6.32 GHz），完全覆盖了5G的n79频段（4.4~5.0 GHz）。

3. 当CoNi@BN的体积分数为44 vol%时，CoNi@BN/PDMS复合材料的λ∥为7.31 W m^-1 K^-1，约为纯PDMS的λ∥（0.64 W m^-1 K^-1）的11.4倍，较相同CoNi和BN体积分数且直接共混的(CoNi/BN)/PDMS复合材料的λ∥（5.52 W m^-1 K^-1）提高了32%。

第一作者：何沐锟

邮箱地址：hemukun@mail.nwpu.edu.cn