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首页> 外文期刊>ACS Macro Letters >Analysis of Slow Modes in Ring Polymers: Threading of Rings Controls Long-Time Relaxation
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Analysis of Slow Modes in Ring Polymers: Threading of Rings Controls Long-Time Relaxation

机译：环聚合物中慢速模式的分析：环的穿线控制长时间松弛

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Atomistic configurations of pure, precisely monodisperse ring poly(ethylene oxide) (PEO) melts accumulated in the course of very long molecular dynamics (MD) simulations at T = 413 K and P = 1 atm have been subjected to a detailed geometric analysis involving three steps (reduction to ensembles of coarse-grained paths, triangulation of the resulting three-dimensional polygons, and analysis of interpenetrations using vector calculus) in order to locate ring ring threading events and quantify their strength and survival times. A variety of threading situations have been identified corresponding to single and multiple penetrations. The percentage of inter-ring threadings that correspond to full penetrations has also been quantified. By repeating the analysis for several PEO melts, the dependence of the degree of inter-ring threading on molecular weight (MW) has been obtained. Simulations with MWs up to 10 times the reported entanglement molecular weight (Me) of linear PEO have revealed several multiple threading events in all systems, with their relative number increasing with increasing MW. Our analysis indicates the existence of strong ring-ring topological interactions, which can last up to several times the corresponding average orientational ring polymer relaxation time. We show that these ring-ring interactions, together with the additional ring-linear threadings the remaining linear impurities, can explain the appearance of slow relaxation modes observed experimentally in entangled rings.
机译：在非常长的分子动力学（MD）模拟过程中，在T = 413 K和P = 1 atm的过程中积累的纯正，精确单分散的环型聚环氧乙烷（PEO）熔体的原子结构已进行了详细的几何分析，涉及三个步骤（还原为粗粒度路径的集合，对生成的三维多边形进行三角剖分以及使用矢量演算对互穿进行分析）以定位环环螺纹事件并量化其强度和生存时间。已经确定了与单次穿透和多次穿透对应的各种线程情况。还已量化了对应于完全穿透的环间螺纹百分比。通过对几种PEO熔体重复分析，已获得环间穿线程度对分子量（MW）的依赖性。用分子量高达线性PEO的纠缠分子量（Me）的10倍进行的模拟显示，在所有系统中都有数个多线程事件，并且它们的相对数量随着MW的增加而增加。我们的分析表明存在强的环-环拓扑相互作用，这种相互作用可以持续长达相应的平均取向环聚合物弛豫时间的几倍。我们表明，这些环-环相互作用，以及其他环-线性螺纹，其余的线性杂质，可以解释在纠缠环中实验观察到的慢弛豫模式的出现。

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