Topological Transition in Multicyclic Chains with Structural Symmetry Inducing Stress-Overshoot Phenomena in Multicyclic/Linear Blends under Biaxial Elongational Flow,Macromolecules

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Topological Transition in Multicyclic Chains with Structural Symmetry Inducing Stress-Overshoot Phenomena in Multicyclic/Linear Blends under Biaxial Elongational Flow
Macromolecules ( IF 5.1 ) Pub Date : 2022-10-28 , DOI: 10.1021/acs.macromol.2c01579
Takahiro Murashima ₁ , Katsumi Hagita ₂ , Toshihiro Kawakatsu ₁

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Blends of multicyclic and linear polymers under biaxial elongational flow were analyzed using coarse-grained molecular dynamics simulations. The multicyclic/linear blends displayed overshoot in the normal stress difference at the start-up of the biaxial elongational flow. This overshoot was steeper for multicyclic/linear blends than for our previously reported monocyclic/linear blends [Murashima, T.; Hagita, K.; Kawakatsu, T. Macromolecules2021,54, 7210–7225]. Investigation of the origin of the overshoot in the multicyclic/linear blends revealed a different mechanism than that previously observed in our monocyclic/linear blends. Specifically, a “topological transition” mechanism comprising a morphological change from the open- to closed-ring state was observed in the multicyclic chains, but not in the monocyclic chains. This topological transition drastically changes the stress of the rings. Although the topological transition was also observed in asymmetric-multicyclic/linear blends, no stress overshoot appeared, owing to the asymmetry in the multicyclic chains. Therefore, we hypothesized that the structural symmetry in multicyclic chains is indispensable for the overshoot behavior to occur. We determined that the topological transition in multicyclic chains with structural symmetry induces the stress-overshoot behavior in multicyclic/linear blends under biaxial elongational flow.

中文翻译：

具有结构对称性的多环链中的拓扑转变导致双轴拉伸流动下多环/线性共混物中的应力超调现象

使用粗粒度分子动力学模拟分析了双轴拉伸流动下的多环和线性聚合物的共混物。多循环/线性共混物在双轴拉伸流动开始时的法向应力差中显示过冲。与我们之前报道的单环/线性共混物相比，多环/线性共混物的这种过冲更陡峭 [Murashima, T.; ; 萩田，K。Kawakatsu, T. Macromolecules 2021, 54, 7210–7225]。对多环/线性共混物中过冲起源的研究揭示了与我们之前在单环/线性共混物中观察到的机制不同的机制。具体来说，一个“拓扑转换在多环链中观察到包含从开环状态到闭环状态的形态变化的机制，但在单环链中没有观察到。这种拓扑转变极大地改变了环的应力。尽管在不对称多环/线性共混物中也观察到拓扑转变，但由于多环链的不对称性，没有出现应力过冲。因此，我们假设多环链中的结构对称性对于发生过冲行为是必不可少的。我们确定具有结构对称性的多环链中的拓扑转变会导致双轴拉伸流动下多环/线性共混物中的应力超调行为。

更新日期：2022-10-28

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