Brownian Dynamics Simulations of Polyrotaxanes

There is great interest in understanding how non-equilibrium dynamics are influenced by polymer topology, particularly in knotted and mechanically interlocking polymers (MIPs), which can occur naturally or be created synthetically. Polyrotaxanes are one such MIP in which cyclic molecules (“macrocycles”) are threaded onto a linear polymer backbone with large capping groups preventing disassembly. Materials derived from polyrotaxanes can possess unusual viscoelastic responses, which may be explained by the configurational entropy of the macrocycles along the backbone. This suggests that the number and distribution of macrocycles within a polyrotaxane can be leveraged to control the rheological properties. Here, we investigate this hypothesis using Brownian dynamics simulations of various polyrotaxane architectures in several different flow conditions, demonstrating how the distribution of macrocycles impacts the resulting structural and dynamical properties.