论文标题
多环状链中的拓扑过渡，具有结构对称性，诱导了双轴伸长流的多环形/线性混合物中的应力跨越现象
Topological transition in multicyclic chains with structural symmetry inducing stress-overshoot phenomena in multicyclic/linear blends under biaxial elongational flow
论文作者
论文摘要
使用粗粒分子动力学模拟分析了双轴伸长流下的多环和线性聚合物的混合物。在双轴伸长流的启动时，在正常的应力差异中显示出多环/线性混合物。对于我们先前报道的单核/线性混合物而言，这种过冲的多环/线性混合物更陡峭[T. T. Murashima，K。Hagita和T. Kawakatsu，Macromolecules，2021，54，7210]。对多环/线性混合物中过期的起源的研究发现，与以前在我们的单核/线性混合物中观察到的机制不同。具体而言，在多环形链中观察到包括从开环状态到封闭状态的形态学变化的“拓扑过渡”机制，但在单核链中未观察到。这种拓扑过渡会大大改变环的应力。尽管在不对称的多环状/线性混合物中也观察到拓扑转变，但由于多环形链中的不对称性，没有应力过冲。因此，我们假设多轮链中的结构对称性对于过冲行为是必不可少的。我们确定具有结构对称性的多环形链中的拓扑跃迁会在双轴伸长流动下诱导多环/线性混合物中的应力跨越行为。
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 biaxial elongational flow. This overshoot was steeper for multicyclic/linear blends than for our previously reported monocyclic/linear blends [T. Murashima, K. Hagita, and T. Kawakatsu, Macromolecules, 2021, 54, 7210]. 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 overshoot behavior to occur. We determined that the topological transition in multicyclic chains with structural symmetry induces stress-overshoot behavior in multicyclic/linear blends under biaxial elongational flow.
