标题： 通过具有可调疏水性的功能化纳米管的水传输 显示英文标题

标题： Water transport through functionalized nanotubes with tunable hydrophobicity

摘要： 分子动力学模拟用于研究由疏水和亲水原子组成的纳米管中水的占据情况和流动情况，这些原子排列在蜂窝晶格上以模拟功能化碳纳米管（CNTs）。我们考虑TIP3P水在(6,6) CNTs的狭窄通道中的单文件运动，通道中亲水原子的比例（f）各不相同。使用了各种亲水原子的排列方式，以创建具有沿管方向分离的疏水/亲水区域以及两种原子随机混合的异质纳米管。发现纳米管通道内的水占据情况随f呈非线性变化，少量的亲水原子（f ~ 0.4）足以引发纳米管的自发连续填充。有趣的是，通道内的平均水分子数和通过纳米管的水通量对亲水原子的具体排列不如对比例f敏感。观察到水通量与f的关系存在两种不同的模式——当f < 0.4时，通量随f近似线性增加，而对于更高的f值，通量几乎不发生变化，类似于水占据情况的变化。我们能够根据疏水和亲水纳米管原子与水之间相互作用强度的线性组合，定义纳米管原子与水氧之间的有效相互作用强度，该强度可以定量地捕捉到观察到的行为。 显示英文摘要

摘要： Molecular dynamics simulations are used to study the occupancy and flow of water through nanotubes comprised of hydrophobic and hydrophilic atoms, which are arranged on a honeycomb lattice to mimic functionalized carbon nanotubes (CNTs). We consider single-file motion of TIP3P water through narrow channels of (6,6) CNTs with varying fractions (f) of hydrophilic atoms. Various arrangements of hydrophilic atoms are used to create heterogeneous nanotubes with separate hydrophobic/hydrophilic domains along the tube as well as random mixtures of the two types of atoms. The water occupancy inside the nanotube channel is found to vary nonlinearly as a function of f, and a small fraction of hydrophilic atoms (f ~ 0.4) are sufficient to induce spontaneous and continuous filling of the nanotube. Interestingly, the average number of water molecules inside the channel and water flux through the nanotube are less sensitive to the specific arrangement of hydrophilic atoms than to the fraction, f. Two different regimes are observed for the water flux dependence on f - an approximately linear increase in flux as a function of f for f < 0.4, and almost no change in flux for higher f values, similar to the change in water occupancy. We are able to define an effective interaction strength between nanotube atoms and water's oxygen, based on a linear combination of interaction strengths between hydrophobic and hydrophilic nanotube atoms and water, that can quantitatively capture the observed behavior.