From Collisions to Bundles: An Adaptive Coarse-Grained Model for the Aggregation of High-Aspect-Ratio Carbon Nanotubes
From Collisions to Bundles: An Adaptive Coarse-Grained Model for the Aggregation of High-Aspect-Ratio Carbon Nanotubes
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DOI：
10.1021/acs.jpcc.9b10479
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发表时间：
2020-04-16
影响因子：
3.7
通讯作者：
Boies, Adam
中科院分区：
文献类型：
--
作者：
Kateris, Nikolaos;Kloza, Philipp A.;Boies, Adam
提出了一个碳纳米管（CNT）系统的自适应中尺度模型。在我们的模型中，碳纳米管被表示为一个链的节点连接拉伸和扭转弹簧来描述链的拉伸和弯曲，与分子间的相互作用通过使用介观Lennard-Jones势计算。通过在模拟过程中动态调整节点间距和数量，实现了计算自适应性，优化了模拟粒子的数量，降低了计算量。自适应模拟比非自适应模拟快5倍，同时定量保留所有系统动态。特别是，该模型使研究的时间尺度的CNT捆绑，导致形成稀释的CNT网络，所谓的气凝胶。这些气凝胶构成了从化学气相沉积合成直接纺制CNT纤维的第一步。了解CNT成束和网络形成的因素是控制CNT纤维微观结构并优化其性能的关键。使用该模型，我们模拟了捆绑动力学的两个碳纳米管与初始点接触，在不同的角度为碳纳米管长度高达10 μ m。我们发现，成束时间是初始碰撞角的递增函数，并且随着CNT长度的增加而遵循幂律，范围从10（-1）到10（3）ns。我们假设，当成束时间变得与CNT束碰撞时间相同时，将形成气凝胶。
We present an adaptive mesoscale model for carbon nanotube (CNT) systems. In our model, CNTs are represented as a chain of nodes connected by tensile and torsion springs to describe stretching and bending of the chain, with intermolecular interactions being calculated by using a mesoscopic Lennard-Jones potential. Computational adaptivity was achieved by dynamically adjusting node spacing and number during the simulation to optimize the number of simulated particles and lower computational effort. Adaptive simulations were up to 5 times faster than nonadaptive ones while quantitatively preserving all system dynamics. In particular, the model enables the study of the time scale of CNT bundling that leads to the formation of dilute CNT networks, so-called aerogels. These aerogels constitute the first step in the direct spinning of CNT fibers from chemical vapor deposition synthesis. Understanding the factors governing CNT bundling and network formation is key to controlling CNT fiber microstructure and therefore optimizing their properties. Using the model, we simulated the bundling dynamics of two CNTs with an initial point contact at varying angles for CNT lengths of up to 10 mu m. We find that bundling times are an increasing function of initial collision angle and follow a power law with increasing CNT length, ranging from 10(-1) to 10(3) ns. We postulate that when the bundling time becomes of the same order as the CNT bundle collision time, the aerogel will form.