Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA.
Nanotechnology. 2010 Jul 2;21(26):265706. doi: 10.1088/0957-4484/21/26/265706. Epub 2010 Jun 10.
Carbon nanotube sheets or films, also known as 'buckypaper', have been proposed for use in actuating, structural and filtration systems, based in part on their unique and robust mechanical properties. Computational modeling of such a fibrous nanostructure is hindered by both the random arrangement of the constituent elements as well as the time- and length-scales accessible to atomistic level molecular dynamics modeling. Here we present a novel in silico assembly procedure based on a coarse-grain model of carbon nanotubes, used to attain a representative mesoscopic buckypaper model that circumvents the need for probabilistic approaches. By variation in assembly parameters, including the initial nanotube density and ratio of nanotube type (single- and double-walled), the porosity of the resulting buckypaper can be varied threefold, from approximately 0.3 to 0.9. Further, through simulation of nanoindentation, the Young's modulus is shown to be tunable through manipulation of nanotube type and density over a range of approximately 0.2-3.1 GPa, in good agreement with experimental findings of the modulus of assembled carbon nanotube films. In addition to carbon nanotubes, the coarse-grain model and assembly process can be adapted for other fibrous nanostructures such as electrospun polymeric composites, high performance nonwoven ballistic materials, or fibrous protein aggregates, facilitating the development and characterization of novel nanomaterials and composites as well as the analysis of biological materials such as protein fiber films and bulk structures.
碳纳米管片或薄膜，也被称为“巴基纸”，因其独特而坚固的机械性能，已被提议用于致动、结构和过滤系统。这种纤维状纳米结构的计算建模受到组成元素的随机排列以及原子级分子动力学建模可访问的时间和长度尺度的阻碍。在这里，我们提出了一种新的基于碳纳米管粗粒模型的计算组装方法，用于获得一种具有代表性的介观巴基纸模型，从而避免了需要概率方法。通过改变组装参数，包括初始纳米管密度和纳米管类型（单壁和双壁）的比例，可以将所得巴基纸的孔隙率在大约 0.3 到 0.9 之间变化三倍。此外，通过模拟纳米压痕，可以通过操纵纳米管类型和密度来调节杨氏模量，范围大约在 0.2-3.1GPa 之间，与组装碳纳米管薄膜的实验发现的模量非常吻合。除了碳纳米管之外，粗粒模型和组装工艺还可以适应其他纤维状纳米结构，如静电纺丝聚合物复合材料、高性能无纺弹道材料或纤维状蛋白质聚集体，从而促进新型纳米材料和复合材料的开发和表征以及对蛋白质纤维膜和体结构等生物材料的分析。
