Topological glass in self-entangled ring polymers*

The dynamics of entangled linear polymers is well understood in terms of the tube model. A remaining challenge in polymer physics is to fully understand the dynamics of ring polymers, which have no chain ends and lie outside the framework of the tube model. In this work, we perform single-molecule DNA experiments to investigate the dynamics of self-entangled ring polymers. We use electric fields to induce self-entanglements in circular DNA molecules, which serve as a minimal system for studying chain entanglement. Our experimental results show that self-threadings give rise to entanglements in ring polymers and can slow down polymer dynamics significantly. We find that strongly entangled circular molecules remain kinetically arrested in a compact state for very long times, thereby providing experimental evidence for a topological glass in ring polymers.