Department of Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112, United States of America.
Nanotechnology. 2019 May 3;30(18):185302. doi: 10.1088/1361-6528/ab012f. Epub 2019 Jan 23.
A three-dimensional (3D) continuum percolation model has been developed on the basis of Monte Carlo simulation to investigate the percolation behavior of an electrically insulating matrix reinforced with multiple conductive fillers of different dimensionalities. Impenetrable fillers of large aspect ratio are found to preferentially align with each other to maximize the packing entropy rather than forming randomly oriented clusters. This entropy-driven transition from isotropic to nematic phase is shown to critically affect the percolation threshold. It suggests that an isotropic phase with a smaller nematic order parameter leads to a reduction in percolation threshold. In addition, a combination of two fillers with different dimensionalities can achieve a working concentration below the percolation threshold of single component system, which is further validated by the experiments of electrical conductivity in multicomponent multidimensional nanocarbon composites.
已经基于蒙特卡罗模拟开发了一种三维（3D）连续体渗流模型，以研究具有不同维度的多个导电填充剂增强的电绝缘基体的渗流行为。发现大纵横比的不可渗透填充剂优先彼此对齐，以最大化堆积熵，而不是形成随机取向的团簇。这种从各向同性到向列相的熵驱动转变被证明会严重影响渗流阈值。这表明具有较小向列序参量的各向同性相导致渗流阈值降低。此外，两种具有不同维度的填充剂的组合可以在低于单一组分系统的渗流阈值的工作浓度下实现，这通过多组分多维纳米碳复合材料的电导率实验得到了进一步验证。
