Matsumoto Masakazu, Yagasaki Takuma, Tanaka Hideki
Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan.
Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan.
J Chem Phys. 2021 Mar 7;154(9):094502. doi: 10.1063/5.0044300.
Stable crystalline structures of confined water can be different from bulk ice. In Paper I [T. Yagasaki et al., J. Chem. Phys. 151, 064702 (2019)] of this study, it was shown, using molecular dynamics (MD) simulations, that a zeolite-like ice structure forms in nanobrushes consisting of (6,6) carbon nanotubes (CNTs) when the CNTs are located in a triangle arrangement. The melting temperature of the zeolite-like ice structure is much higher than the melting temperature of ice I when the distance between the surfaces of CNTs is ∼0.94 nm, which is the best spacing for the bilayer structure of water. In this paper, we perform MD simulations of nanobrushes of CNTs that are different from (6,6) CNTs in radius. Several new porous ice structures form spontaneously in the MD simulations. A stable porous ice forms when the radius of its cavities matches the radius of the CNTs well. All cylindrical porous ice structures found in this study can be decomposed into a small number of structural blocks. We provide a new protocol to classify cylindrical porous ice crystals on the basis of this decomposition.
受限水的稳定晶体结构可能与块状冰不同。在本研究的第一篇论文 [T. 矢崎等人，《化学物理杂志》151, 064702 (2019)] 中，通过分子动力学 (MD) 模拟表明，当 (6,6) 碳纳米管 (CNT) 呈三角形排列时，在由其组成的纳米刷中会形成类似沸石的冰结构。当碳纳米管表面之间的距离约为0.94纳米时，类似沸石的冰结构的熔化温度远高于冰I的熔化温度，这是水双层结构的最佳间距。在本文中，我们对半径不同于 (6,6) 碳纳米管的碳纳米管纳米刷进行了分子动力学模拟。在分子动力学模拟中自发形成了几种新的多孔冰结构。当其空腔半径与碳纳米管半径匹配良好时，会形成稳定的多孔冰。本研究中发现的所有圆柱形多孔冰结构都可以分解为少量结构单元。我们基于这种分解提供了一种对圆柱形多孔冰晶进行分类的新方法。
