Centre for Computational Sciences, University College London, 20 Gordon Street, London, WCH1 0AJ, UK.
Phys Chem Chem Phys. 2019 Mar 6;21(10):5716-5722. doi: 10.1039/c8cp07796g.
Mechanical exfoliation techniques are widely used to create high quality graphene samples for analytical use. Increasingly, mechanical methods are used to create large quantities of graphene, yet there is surprisingly little molecular insight into the mechanisms involved. We study the exfoliation of graphene with sticky tape using molecular dynamics. This is made possible by using a recently developed molecular dynamics forcefield, GraFF, to represent graphene's dispersion interactions. For nano-sized flakes we observe two different mechanisms depending on the polymer-adhesive used. A peeling mechanism which mixes shearing and normal mode exfoliation promotes synthesis of graphene rather than many-layered graphite. Armed with this new chemical insight we discuss the experimental methods that could preferentially produce graphene by mechanical exfoliation. We also introduce a mathematical model describing the repeated exfoliation of graphite.
机械剥离技术被广泛应用于分析用途的高质量石墨烯样品的制备。越来越多的机械方法被用于制备大量的石墨烯，但对于所涉及的机制，人们的分子认识却惊人地有限。我们使用分子动力学研究了粘性胶带对石墨烯的剥离。这得益于最近开发的分子动力学力场 GraFF，它可以表示石墨烯的色散相互作用。对于纳米级薄片，我们观察到两种不同的机制，这取决于所使用的聚合物-粘合剂。一种混合了剪切和法向模式剥离的剥离机制促进了石墨烯的合成，而不是多层石墨的合成。有了这种新的化学洞察力，我们讨论了通过机械剥离优先制备石墨烯的实验方法。我们还引入了一个描述石墨重复剥离的数学模型。
