Jiang Jianwen, Sandler Stanley I
Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576.
Langmuir. 2006 Aug 15;22(17):7391-9. doi: 10.1021/la0608720.
Capillary phase transitions of linear (from C(1) to C(12)) and branched (C(5) isomers) alkanes in single-walled carbon nanotubes have been investigated using the gauge-cell Monte Carlo simulation. The isotherm at a supercritical temperature increases monotonically with chemical potential and coincides with that from the traditional grand canonical Monte Carlo simulation, whereas the isotherm at a subcritical temperature exhibits a sigmoid van der Waals loop including stable, metastable, and unstable regions. Along this loop, the coexisting phases are determined using an Maxwell equal-area construction. A generic confinement effect is found that reduces the saturation chemical potential, lowers the critical temperature, increases the critical density, and shrinks the phase envelope. The effect is greater in a smaller diameter nanotube and is greater in a nanotube than in a nanoslit.
利用规范单元蒙特卡罗模拟研究了单壁碳纳米管中线性（从C(1)到C(12)）和支链（C(5)异构体）烷烃的毛细管相变。超临界温度下的等温线随化学势单调增加，且与传统巨正则蒙特卡罗模拟的等温线一致，而亚临界温度下的等温线呈现出包含稳定、亚稳和不稳定区域的S形范德瓦尔斯回路。沿着这个回路，使用麦克斯韦等面积构造法确定共存相。发现了一种普遍的限制效应，它降低了饱和化学势，降低了临界温度，增加了临界密度，并缩小了相包络。这种效应在直径较小的纳米管中更大，且在纳米管中比在纳米狭缝中更大。
