Effect of chain length on structure and dynamics in a melt of semiflexible rings
Effect of chain length on structure and dynamics in a melt of semiflexible rings
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链长对半柔性环熔体结构和动力学的影响
DOI：
10.1209/0295-5075/130/56001
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
张博凯
中科院分区：
文献类型：
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作者：
李健;张博凯
采用分子动力学模拟方法研究了熔体中半柔性环的结构和动力学。我们的研究主要集中在链长效应。我们观察到环在中等长度尺度上链内结构因子的幂律。报道了1和3在不同长度尺度下的分形维数。通过对链内结构因子的解析表达式，认为分形维数的值分别与杆和环的特征有关。随着链长的增加，键角的高斯分布宽度和键角的平均值均有显著增加。此外，我们发现链长诱导了径向分布函数和短程吸引有效势的超软球状行为。结合自聚中间散射函数的分离，我们提出了短程吸引有效势的存在是环形聚合物中互穿和聚簇出现的结构信号。最后，发现半柔性环熔体中扩散衰减指数随链长显著增加。半柔性环的相互渗透被认为是指数大的原因。
We investigate structure and dynamics of semiflexible rings in a melt by molecular dynamics simulation. Our research mainly focuses on chain length effect. We observe a power law of the intrachain structure factor of rings at intermediate length scale. The fractal dimensions of 1 and 3 at different length scales are reported. By analytical expression for the intrachain structure factor, the value of fractal dimensions is considered to be related to the features of rod and ring, respectively. With the increase of the chain length, the width of the Gaussian distribution of bond angles and the mean value of bond angles show significant increases. Further, we find that chain length induces ultra-soft sphere-like behavior in radial distribution function and short-range attractive effective potential. By combining this with the separation between self- and collective intermediate scattering function, we propose that the presence of the short-range attractive effective potential is the structural signal of the emergence of interpenetration and cluster in ring polymers. Finally, a significant increase of the decay exponent of diffusion with chain length in the melt of semiflexible rings is found. Interpenetration of semiflexible rings is supposed to be responsible for the large value of exponent.