Topological Effects in Isolated Poly[n]catenanes: Molecular Dynamics Simulations and Rouse Mode Analysis

Poly­[n]­catenanes are mechanically interlocked polymers consisting of interlocking ring molecules. Over the years, researchers have speculated that the permanent topological interactions within the poly­[n]­catenane backbone could lead to unique dynamical behaviors. To investigate these unusual polymers, molecular dynamics simulations of isolated poly­[n]­catenanes have been conducted, along with a Rouse mode analysis. Owing to the mechanical bonds within the molecule, the dynamics of poly­[n]­catenanes at short length scales are significantly slowed and the distribution of relaxation times is broadened; these same behaviors have been observed in melts of linear polymers and are associated with entanglement. Despite these entanglement-like effects, at large length scales poly­[n]­catenanes do not relax much slower than isolated linear polymers and are less strongly impacted by increased segmental stiffness.