Coupled effects of concentration and chain architecture on non-equilibrium polymer solution dynamics

The dynamics of semidilute polymer solutions are of practical importance to soft materials. Strong flows during coating and printing processes result in non-equilibrium polymer conformations that ultimately control material properties. Despite their practical importance, we have not yet achieved a complete molecular-scale understanding of non-dilute polymer solutions due to a complex interplay of interpolymer and hydrodynamic interactions (HI) that are challenging to characterize and expensive to simulate. In this work, we develop an understanding of the combined effects of concentration, chain architecture, and flow using a new simulation method that enables rapid and efficient simulation of non-dilute polymer solutions with long-range HI. Using this approach, we study the dynamics of semidilute ring-linear polymer blends at concentrations 0.1-3.0 c* in planar extensional flow. In contrast to pure polymer solutions, ring-linear blends exhibit unique conformational dynamics. Importantly, our results highlight the prevalence of strong ring-linear topological constraints and large conformational fluctuations due to local flow instabilities. These results are consistent with single-molecule observations of labeled linear and ring DNA chains in semidilute solutions.