Zandieh Azadeh, Buahom Piyapong, Baradaran Shokouhi Elnaz, Mark Lun Howe, Rahmati Reza, Aghababaei Tafreshi Omid, Hamidinejad Mahdi, Mandelis Andreas, Kim Keun Su, Park Chul B
Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, M5S 3G8, Canada.
Center for Advanced Diffusion-Wave and Photoacoustic Technologies and Institute for Advanced Non-Destructive and Non-Invasive Diagnostic Technologies, University of Toronto, Toronto, ON, M5S 3G8, Canada.
Small. 2024 Nov;20(48):e2404189. doi: 10.1002/smll.202404189. Epub 2024 Aug 7.
An ideal dielectric material for microelectronic devices requires a combination of high anisotropic thermal conductivity and low dielectric constant (ɛ') and loss (tan δ). Polymer composites of boron nitride nanotubes (BNNTs), which offer excellent thermal and dielectric properties, show promise for developing these dielectric polymer composites. Herein, a simple method for fabricating polymer/BNNT composites with high directional thermal conductivity and excellent dielectric properties is presented. The nanocomposites with directionally aligned BNNTs are fabricated through melt-compounding and in situ fibrillation, followed by sintering the fibrous nanocomposites. The fabricated nanocomposites show a significant enhancement in thermal properties, with an in-plane thermal conductivity (K) of 1.8 WmK-a 450% increase-yielding a high anisotropy ratio (K/K) of 36, a 1700% improvement over isotropic samples containing only 7.2 vol% BNNT. These samples exhibit a 120% faster in-plane heat dissipation compared to the through-plane within 2 s. Additionally, they display low ɛ' of ≈3.2 and extremely low tan δ of ≈0.014 at 1 kHz. These results indicate that this method provides a new avenue for designing and creating polymer composites with enhanced directional heat dissipation properties along with high K, suitable for thermal management applications in electronic packaging, thermal interface materials, and passive cooling systems.
用于微电子器件的理想介电材料需要兼具高各向异性热导率以及低介电常数（ε'）和损耗（tan δ）。具有优异热性能和介电性能的氮化硼纳米管（BNNTs）聚合物复合材料，在开发这些介电聚合物复合材料方面展现出了潜力。在此，我们提出了一种制备具有高定向热导率和优异介电性能的聚合物/BNNT复合材料的简单方法。通过熔融共混和原位原纤化制备出具有定向排列BNNTs的纳米复合材料，随后对纤维状纳米复合材料进行烧结。所制备的纳米复合材料在热性能方面有显著提升，其面内热导率（K）为1.8 WmK⁻¹（提高了450%），产生了36的高各向异性比（K/K⊥），相较于仅含有7.2 vol% BNNT的各向同性样品提高了1700%。在2秒内，这些样品的面内热耗散速度比穿面热耗散速度快120%。此外，在1 kHz时，它们显示出约3.2的低ε'和约0.014的极低tan δ。这些结果表明，该方法为设计和制造具有增强的定向散热性能以及高K值的聚合物复合材料提供了一条新途径，适用于电子封装、热界面材料和被动冷却系统中的热管理应用。
