Di Pierro Alessandro, Mortazavi Bohayra, Noori Hamidreza, Rabczuk Timon, Fina Alberto
Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, Alessandria Campus, Viale Teresa Michel 5, 15121 Alessandria, Italy.
Department of Mathematics and Physics, Leibniz Universität Hannover, Appelstraße 11, 30167 Hannover, Germany.
Nanomaterials (Basel). 2021 May 11;11(5):1252. doi: 10.3390/nano11051252.
Graphene and borophene are highly attractive two-dimensional materials with outstanding physical properties. In this study we employed combined atomistic continuum multi-scale modeling to explore the effective thermal conductivity of polymer nanocomposites made of polydimethylsiloxane (PDMS) polymer as the matrix and graphene and borophene as nanofillers. PDMS is a versatile polymer due to its chemical inertia, flexibility and a wide range of properties that can be tuned during synthesis. We first conducted classical Molecular Dynamics (MD) simulations to calculate the thermal conductance at the interfaces between graphene and PDMS and between borophene and PDMS. Acquired results confirm that the interfacial thermal conductance between nanosheets and polymer increases from the single-layer to multilayered nanosheets and finally converges, in the case of graphene, to about 30 MWm K and, for borophene, up to 33 MWm K. The data provided by the atomistic simulations were then used in the Finite Element Method (FEM) simulations to evaluate the effective thermal conductivity of polymer nanocomposites at the continuum level. We explored the effects of nanofiller type, volume content, geometry aspect ratio and thickness on the nanocomposite effective thermal conductivity. As a very interesting finding, we found that borophene nanosheets, despite having almost two orders of magnitude lower thermal conductivity than graphene, can yield very close enhancement in the effective thermal conductivity in comparison with graphene, particularly for low volume content and small aspect ratios and thicknesses. We conclude that, for the polymer-based nanocomposites, significant improvement in the thermal conductivity can be reached by improving the bonding between the fillers and polymer, or in other words, by enhancing the thermal conductance at the interface. By taking into account the high electrical conductivity of borophene, our results suggest borophene nanosheets as promising nanofillers to simultaneously enhance the polymers' thermal and electrical conductivity.
石墨烯和硼烯是极具吸引力的二维材料，具有出色的物理性能。在本研究中，我们采用原子连续体多尺度联合建模方法，来探究以聚二甲基硅氧烷（PDMS）聚合物为基体、石墨烯和硼烯为纳米填料的聚合物纳米复合材料的有效热导率。PDMS是一种通用聚合物，因其化学惰性、柔韧性以及在合成过程中可调节的广泛性能而备受关注。我们首先进行了经典分子动力学（MD）模拟，以计算石墨烯与PDMS以及硼烯与PDMS之间界面的热导率。获得的结果证实，纳米片与聚合物之间的界面热导率从单层纳米片增加到多层纳米片，最终收敛，对于石墨烯而言，收敛到约30 MWm²K，对于硼烯而言，高达33 MWm²K。然后，将原子模拟提供的数据用于有限元方法（FEM）模拟，以评估聚合物纳米复合材料在连续体水平上的有效热导率。我们探究了纳米填料类型、体积含量、几何纵横比和厚度对纳米复合材料有效热导率的影响。一个非常有趣的发现是，我们发现硼烯纳米片尽管热导率比石墨烯低近两个数量级，但与石墨烯相比，在有效热导率方面能产生非常接近的增强效果，特别是对于低体积含量以及小纵横比和厚度的情况。我们得出结论，对于聚合物基纳米复合材料，通过改善填料与聚合物之间的结合，或者换句话说，通过增强界面处的热导率，可以实现热导率的显著提高。考虑到硼烯的高电导率，我们的结果表明硼烯纳米片是有前景的纳米填料，可同时提高聚合物的热导率和电导率。
