Molecular dynamics simulations of active entangled polymers reptating through a passive mesh

Abstract

The dynamics of active entangled chains using molecular dynamics simulations of a modified Kremer–Grest model. The active chains are diluted in a mesh of very long passive linear chains, to avoid constraint release effects, and an active force is applied to the monomers in a way that it imparts a constant polar drift velocity along the primitive path. The simulation results show that, over a wide range of activity values, the conformational properties of the chains and the tubes are not affected, but the dynamics of the chains are strongly modified. Despite not having an explicit tube, the simulations verify the predictions of the active reptation theory very accurately, including a diffusion coefficient that becomes independent of the molecular weight at moderate values of the activity and a relaxation that results in low viscosity. Overall, this work provides information on the study of active entangled polymers, giving a route map for studying this phenomenon and an efficient way of simulating linear active polymers with a markedly preferential direction along the contour that reproduces the physics of active reptation theory.