title: Slowing down of ring polymer diffusion caused by inter-ring threading.
abstract: Diffusion of long ring polymers in a melt is much slower than the reorganization of their internal structures. While direct evidence for entanglements has not been observed in the long ring polymers unlike linear polymer melts, threading between the rings is suspected to be the main reason for slowing down of ring polymer diffusion. It is, however, difficult to define the threading configuration between two rings because the rings have no chain end. In this work, evidence for threading dynamics of ring polymers is presented by using molecular dynamics simulation and applying a novel analysis method. The simulation results are analyzed in terms of the statistics of persistence and exchange times that have proved useful in studying heterogeneous dynamics of glassy systems. It is found that the threading time of ring polymer melts increases more rapidly with the degree of polymerization than that of linear polymer melts. This indicates that threaded ring polymers cannot diffuse until an unthreading event occurs, which results in the slowing down of ring polymer diffusion.
authors.affiliation: Department of Chemistry, Seoul National University, Seoul, 151-747, Korea.
authors.forename: Eunsang
authors.initials: E
authors.lastname: Lee
authors.affiliation: Department of Chemistry, Seoul National University, Seoul, 151-747, Korea.
authors.forename: Soree
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Chemistry, Seoul National University, Seoul, 151-747, Korea.
authors.forename: YounJoon
authors.initials: Y
authors.lastname: Jung
mesh_terms: D004058:Diffusion; D056004:Molecular Dynamics Simulation; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D011108:Polymers
keywords: diffusion; persistence and exchange time; ring polymers; scaling; threading dynamics