Unraveling the Glass-like Dynamic Heterogeneity in Ring Polymer Melts: From Semiflexible to Stiff Chain

Ring polymers are an intriguing class of polymers withunique physicalproperties, and understanding their behavior is important for developingaccurate theoretical models. In this study, we investigate the effectof chain stiffness and monomer density on the static and dynamic behaviorsof ring polymer melts using molecular dynamics simulations. Our firstfocus is on the non-Gaussian parameter of center-of-mass displacementas a measure of dynamic heterogeneity, which is commonly observedin glass-forming liquids. We find that the non-Gaussianity in thedisplacement distribution increases with the monomer density and stiffnessof the polymer chains, suggesting that excluded volume interactionsbetween centers of mass have a strong effect on the dynamics of ringpolymers. We then analyze the relationship between the radius of gyrationand monomer density for semiflexible and stiff ring polymers. Ourresults indicate that the relationship between the two varies withchain stiffness, which can be attributed to the competition betweenrepulsive forces inside the ring and from adjacent rings. Finally,we study the dynamics of bond-breakage virtually connected betweenthe centers of mass of rings to analyze the exchanges of intermolecularnetworks of bonds. Our results demonstrate that the dynamic heterogeneityof bond-breakage is coupled with the non-Gaussianity in ring polymermelts, highlighting the importance of the bond-breaking method indetermining the intermolecular dynamics of ring polymer melts. Overall,our study sheds light on the factors that govern the dynamic behaviorsof ring polymers.

Automated summary

This study investigates the static and dynamic behavior of ring polymer melts by molecular dynamics simulations, focusing on the effect of chain stiffness and monomer density. It is found that the dynamics of ring polymers are influenced by excluded volume interactions between centers of mass, as indicated by the increasing non-Gaussianity in the displacement distribution with higher monomer density and stiffness. The relationship between the radius of gyration and monomer density varies with chain stiffness, which can be attributed to the competition between repulsive forces inside and between rings. The dynamic heterogeneity of bond-breakage is coupled with the non-Gaussianity in ring polymer melts, emphasizing the importance of the bond-breaking method in determining the intermolecular dynamics. Overall, this study provides insights into the factors governing the dynamic behaviors of ring polymers.