Cluster Glasses of Semiflexible Ring Polymers

TL;DR

This study uses computer simulations to explore the unique glassy behavior of concentrated semiflexible ring polymers, revealing a novel decoupling of self and collective dynamics and a new mechanism of glass formation.

Contribution

It introduces the first detailed simulation analysis of glassy dynamics in semiflexible ring polymers, highlighting their distinct self-collective decoupling and clustering behavior.

Findings

Decoupling of self- and collective motions in ring polymers.

Observation of slow relaxation indicating incipient glass transition.

Fast exchange and diffusion of individual rings within clusters.

Abstract

We present computer simulations of concentrated solutions of unknotted nonconcatenated semiflexible ring polymers. Unlike in their flexible counterparts, shrinking involves a strong energetic penalty, favoring interpenetration and clustering of the rings. We investigate the slow dynamics of the centers-of-mass of the rings in the amorphous cluster phase, consisting of disordered columns of oblate rings penetrated by bundles of prolate ones. Scattering functions reveal a striking decoupling of self- and collective motions. Correlations between centers-of-mass exhibit slow relaxation, as expected for an incipient glass transition, indicating the dynamic arrest of the cluster positions. However, self-correlations decay at much shorter time scales. This feature is a manifestation of the fast, continuous exchange and diffusion of the individual rings over the matrix of clusters. Our results reveal a novel scenario of glass-formation in a simple monodisperse system, characterized by self-collective decoupling, soft caging and mild dynamic heterogeneity.