Liu Li, Han Liping, Chen Tao, Li Junpeng, Qian Zhuo, Gan Guoyou
Faculty of Material Science and Engineering, Kunming University of Science and Technology, Kunming 650093, People's Republic of China.
School of Electronic Information and Electrical Engineering, Chongqing University of Arts and Sciences, Chongqing 402160, People's Republic of China.
Langmuir. 2024 Sep 12. doi: 10.1021/acs.langmuir.4c02312.
Thermal interface materials play a pivotal role in efficiently transferring heat from heating devices to thermal management components, thereby reducing the risk of component degradation due to overheating. In this study, we propose a strategy for enhancing the out-of-plane thermal conductivity (TC) of composite materials by fabricating a three-dimensional (3D) thermal network within a polydimethylsiloxane (PDMS) matrix. Specifically, the composite material was designed to incorporate a dense thermal network comprising hexagonal boron nitride nanosheets (BNNSs) and nanodiamonds (NDs). The fabrication process commenced with the preparation of BNNSs through liquid-phase exfoliation, followed by the creation of a 3D BNNSs-NDs/polyimide aerogel thermal framework using a unidirectional solidification ice templating method and subsequent heat treatment. Vacuum impregnation and curing were then employed to finalize the production of the 3D BNNSs-NDs/PDMS composite material. Characterization analyses indicated that the addition of NDs filled the voids between BNNSs, leading to the densification of the thermal framework pore walls and the establishment of additional thermal pathways. Impressively, with concentrations of BNNSs and NDs of 17.99 and 7.71 wt %, respectively, the out-of-plane TC of the 3D BNNSs-NDs/PDMS composite material reached 1.623 W m K, marking notable enhancements of 754.21% and 256.70% compared to those of pure PDMS and composites prepared via direct blending with randomly distributed BNNSs and NDs, respectively. Furthermore, the 3D BNNSs-NDs thermal framework improved the compressive strength and the dimensional stability of the composite material. Finite element simulations additionally confirmed the synergistic improvement of the TC achieved through the combination of BNNSs and NDs, demonstrating that the 3D BNNSs-NDs/PDMS composite material displayed superior heat conduction and a greater density of thermal pathways compared to those of its counterparts, including 3D BNNSs/PDMS and 3D NDs/PDMS composite materials. In summary, this work presents a strategy for enhancing the out-of-plane TC of polymer-based composite materials by incorporating vertically aligned thermal networks.
热界面材料在将热量从加热设备有效传递到热管理组件方面起着关键作用，从而降低因过热导致组件退化的风险。在本研究中，我们提出了一种策略，通过在聚二甲基硅氧烷（PDMS）基质中构建三维（3D）热网络来提高复合材料的面外热导率（TC）。具体而言，该复合材料被设计为包含由六方氮化硼纳米片（BNNSs）和纳米金刚石（NDs）组成的致密热网络。制备过程首先通过液相剥离法制备BNNSs，然后使用单向凝固冰模板法创建3D BNNSs-NDs/聚酰亚胺气凝胶热框架并进行后续热处理。接着采用真空浸渍和固化工艺最终制备出3D BNNSs-NDs/PDMS复合材料。表征分析表明，添加NDs填充了BNNSs之间的空隙，导致热框架孔壁致密化并建立了额外的热传导路径。令人印象深刻的是，当BNNSs和NDs的浓度分别为17.99 wt%和7.71 wt%时，3D BNNSs-NDs/PDMS复合材料的面外TC达到1.623 W m⁻¹ K⁻¹，与纯PDMS以及通过将BNNSs和NDs随机分布直接共混制备的复合材料相比，分别显著提高了754.21%和256.70%。此外，3D BNNSs-NDs热框架提高了复合材料的抗压强度和尺寸稳定性。有限元模拟进一步证实了通过BNNSs和NDs组合实现的TC协同提高，表明3D BNNSs-NDs/PDMS复合材料与其同类材料（包括3D BNNSs/PDMS和3D NDs/PDMS复合材料）相比表现出卓越的热传导性能和更高的热传导路径密度。总之，这项工作提出了一种通过引入垂直排列的热网络来提高聚合物基复合材料面外TC的策略。
