Michieletto Davide, Nahali Negar, Rosa Angelo
School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, Scotland, United Kingdom.
SISSA-Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, 34136 Trieste, Italy.
Phys Rev Lett. 2017 Nov 10;119(19):197801. doi: 10.1103/PhysRevLett.119.197801. Epub 2017 Nov 7.
Understanding how topological constraints affect the dynamics of polymers in solution is at the basis of any polymer theory and it is particularly needed for melts of rings. These polymers fold as crumpled and space-filling objects and, yet, they display a large number of topological constraints. To understand their role, here we systematically probe the response of solutions of rings at various densities to "random pinning" perturbations. We show that these perturbations trigger non-Gaussian and heterogeneous dynamics, eventually leading to nonergodic and glassy behavior. We then derive universal scaling relations for the values of solution density and polymer length marking the onset of vitrification in unperturbed solutions. Finally, we directly connect the heterogeneous dynamics of the rings with their spatial organization and mutual interpenetration. Our results suggest that deviations from the typical behavior observed in systems of linear polymers may originate from architecture-specific (threading) topological constraints.
理解拓扑约束如何影响聚合物在溶液中的动力学是任何聚合物理论的基础，对于环状聚合物熔体尤为必要。这些聚合物折叠成皱缩且充满空间的物体，然而，它们表现出大量的拓扑约束。为了理解它们的作用，我们在此系统地探究了不同密度的环状聚合物溶液对“随机钉扎”扰动的响应。我们表明，这些扰动引发非高斯和非均匀动力学，最终导致非遍历和玻璃态行为。然后，我们推导了未受扰动溶液中标志着玻璃化转变开始的溶液密度和聚合物长度值的通用标度关系。最后，我们将环状聚合物的非均匀动力学与其空间组织和相互穿透直接联系起来。我们的结果表明，与线性聚合物体系中观察到的典型行为的偏差可能源于特定结构（贯穿）的拓扑约束。
