Twisted and coiled ultralong multilayer graphene ribbons
Twisted and coiled ultralong multilayer graphene ribbons
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DOI：
10.1088/0965-0393/19/5/054003
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发表时间：
2011-07-01
影响因子：
1.8
通讯作者：
Buehler, Markus J.
中科院分区：
文献类型：
--
作者：
Cranford, Steven;Buehler, Markus J.
多层石墨烯片和纳米带的力学行为和性能由于其在电子、结构和热方面的潜在应用而成为近年来深入研究的课题。有效性质的计算范围从分子动力学模拟到使用结构力学连续体模型。本文通过全原子模拟获得了结构和弹性参数，并利用具有旋转弹簧势的粗粒珠簧元件建立了石墨烯片的二维介观模型。通过弹性应变能，原子和中尺度模型之间的能量守恒的断言被强制执行，以达到模型参数，包括法向和剪切应变，面外弯曲和分子内相互作用。然后，我们应用我们的介观模型来研究扭曲的超长多层石墨烯带的结构和构象行为，这些带的长度为数百纳米，代表了数百万个单个原子，超出了完全原子分子动力学的可访问范围。我们发现从扭曲（鞍状）结构到螺旋（线圈状）结构的明显转变是施加旋转和石墨烯层数的函数。此外，对于单层石墨烯带，由于表面粘附，在离散旋转时出现多种稳定构型。这里开发和应用的模型可以更广泛地用于研究其他二维膜和带状系统的特性，用于中尺度分层材料设计。
The mechanical behavior and properties of multilayer graphene sheets and nanoribbons have been a subject of intensive research in recent years, due to their potential in electronic, structural and thermal applications. Calculations of effective properties range from molecular dynamic simulations to use of structural mechanical continuum models. Here, structural and elastic parameters are obtained via full atomistic simulations, and a two-dimensional mesoscopic model for a sheet of graphene is developed utilizing coarse-grain bead-spring elements with rotational-spring potentials. The assertion of energy conservation between atomistic and mesoscale models through elastic strain energy is enforced to arrive at model parameters, incorporating normal and shear strains, out-of-plane bending and intramolecular interactions. We then apply our mesoscopic model to investigate the structure and conformational behavior of twisted ultralong multilayer graphene ribbons with lengths of hundreds of nanometers, representing several millions of individual atoms, beyond the accessible regime of full atomistic molecular dynamics. We find a distinct transition from a twisted (saddle-like) configuration to a helical (coil-like) configuration as a function of imposed rotation and number of graphene layers. Further, for single layer graphene ribbons, multiple, stable configurations occur at discrete rotations due to the surface adhesion. The model developed and applied here can be more generally used to investigate properties of other two-dimensional membrane and ribbon-like systems for mesoscale hierarchical material design.