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arXiv 2201.03830cond-mat.soft
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拓扑结构对流体-流体界面处聚合物链静态与动态特性的影响:分子动力学模拟研究

Effect of topology on the statics and dynamics of a polymer chain at the fluid-fluid interface: a molecular dynamics simulation study

Jenis Thongam, Lenin S. Shagolsem

AI总结:

本研究利用分子动力学模拟,探讨了线性、环状和三叶结三种拓扑结构对流体界面处聚合物链静态与动态特性的影响,发现拓扑结构显著改变链伸展和自扩散常数,但不影响质心均方位移的扩散指数。

摘要:

本文通过分子动力学模拟研究了链拓扑结构对两种不相溶流体界面处链的静态与动态特性的影响。对于三种拓扑结构不同的链,即具有相同分子量的线性链、环链和三叶结链,研究了改变聚合物-流体及流体-流体相互作用性质对流体界面宽度、链构象、形状及链动力学的影响。对于锐界面二元流体系统,界面宽度对拓扑结构和聚合物-流体相互作用性质均不敏感,而在弱界面系统中则观察到微弱的非单调变化。垂直于界面平面的链伸展受拓扑结构显著影响,由于额外约束,三叶结链的伸展值相比线性与环链最大。瞬时形状亦通过形状参数进行了量化。此外,观察到质心均方位移(MSD)的定性行为与拓扑结构无关,即所有链类型均表现出相同的扩散指数 $α~(\approx 1)$。然而,自扩散常数依赖于拓扑结构,且三叶结链的自扩散常数最大。关于单体MSD早期行为的一个有趣观察是,在亚扩散区域内,不同参数下的 $α$ 值(与拓扑结构无关)被划分为两个不同区间(0.52--0.59 和 0.62--0.67),这与聚合物-流体相互作用范围低于或高于等于纯流体相自相互作用阈值的链构象差异有关。

英文摘要:

The effect of chain topology on the statics and dynamics of chain at the interface of two immiscible fluids is studied by means of molecular dynamics simulations. For three topologically different chains, namely, linear, ring, and trefoil-knot of same molecular weight the effect of varying both polymer--fluid and fluid--fluid interaction nature on the width of the fluid interface, chain conformation, shape, and chain dynamics. For sharp-interface binary-fluid system, the interface width is insensitive to both topology and polymer-fluid interaction nature, while a weak non-monotonic variation is seen for weak-interface system. Chain extension normal to the interface plane is significantly affected by the topology with trefoil-knot chain, due to the additional constraint, has the largest value compared to both linear and ring polymers. Instantaneous shapes are also quantified through shape parameters. Furthermore, it is observed that the qualitative behavior of center of mass mean-square displacement (MSD) is independent of topology, i.e., all the chain types show same diffusion exponent $α~(\approx 1)$. However, the self-diffusion constant depends on the topology and it is largest for trefoil-knot chain. An interesting observation pertaining the early time behavior of monomeric-MSD is that, within the sub-diffusive regime, the values of $α$ for different parameters (independent of topology) are grouped into two distinct ranges (0.52--0.59 and 0.62--0.67) which is related to the different chain conformation for polymer-fluid interaction range below and above a threshold value equal to that of the self-interaction of the pure fluid phase.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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