回转半径
指数
戒指(化学)
缩放比例
聚合物
放松(心理学)
高分子
报告
扩散
链条(单位)
线型聚合物
化学
材料科学
化学物理
热力学
物理
核磁共振
数学
量子力学
几何学
哲学
有机化学
社会心理学
生物化学
语言学
心理学
作者
Jiangyang Mo,Jian Wang,Zhenhua Wang,Yuyuan Lu,Lijia An
出处
期刊:Macromolecules
[American Chemical Society]
日期:2022-02-15
卷期号:55 (5): 1505-1514
被引量:8
标识
DOI:10.1021/acs.macromol.1c02388
摘要
Using dynamic Monte Carlo simulations based on the bond-fluctuation model, we systematically investigate the static and dynamic properties of a tracer ring polymer in a melt composed of linear polymers. Our results reveal that the mean-square radius of gyration of a cyclic polymer is independent of the topological constraints between the ring and linear chains. The scaling exponent (ν) of the radius of gyration Rg ∼ NRν, where NR is the ring chain length, increases from 0.5 to 0.6 as the length of the linear matrix chains, NL, decreases, which lies between the two values reported by Iyer et al. [ Macromolecules 2007, 40, 5995] and Lang et al. [ Macromolecules 2012, 45, 7642]. We find that both the structural relaxation time and self-diffusion coefficient are nearly independent of NL for a short ring chain (NR = 20) and the scaling exponents of NL for the self-diffusion coefficient are between −1 and −2 for large NR (NR ≥ 100), which cannot be understood by existing mechanisms, including the restraint reptation mechanism, the once-threaded mechanism, and the constraint release mechanism. Furthermore, we propose a “touch-threading” mechanism, which could be regarded as an important supplement to the above mechanisms, to describe the structural relaxation and translational diffusion of a tracer ring in a linear melt. In addition, when NL is large, the structural relaxation and translational diffusion of the tracer ring are decoupled, resulting in a breakdown of the extended Stokes–Einstein relation. These results provide fundamental insights into the properties of the ring-linear blends.
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