Dynamics and Rheology of Ring-Linear Blend Semidilute Solutions in Extensional Flow: Single Molecule Experiments

Abstract

Ring polymers exhibit unique flow properties due to their closed chain topology. Despite recent progress, we have not yet achieved a full understanding of the nonequilibrium flow behavior of rings in nondilute solutions where intermolecular interactions greatly influence chain dynamics. In this work, we directly observe the dynamics of DNA rings in semidilute ring-linear polymer blends using single molecule techniques. We systematically investigate ring polymer relaxation dynamics from high extension and transient and steady-state stretching dynamics in planar extensional flow for a series of ring-linear blends with varying ring fraction. Our results show multiple molecular sub-populations for ring relaxation in ring-linear blends, as well as large conformational fluctuations for rings in steady extensional flow, even long after the initial transient stretching process has subsided. We further quantify the magnitude and characteristic timescales of ring conformational fluctuations as a function of blend composition. Interestingly, we find that the magnitude of ring conformational fluctuations follows a non-monotonic response with increasing ring fraction, first increasing at low ring fraction and then substantially decreasing at large ring fraction in ring-linear blends. A unique set of ring polymer conformations are observed during the transient stretching process, which highlights the prevalence of molecular individualism and supports the notion of complex intermolecular interactions in ring-linear polymer blends. Together with results from molecular simulations, our results suggest that ring conformational fluctuations arise due to ring-linear threading and intermolecular hydrodynamic interactions (HI). Taken together, our results provide a new molecular understanding of ring polymer dynamics in ring-linear blends in nonequilibrium flow.

17 pages, 9 figures

References in corpus (3)

• Topological Linking Drives Anomalous Thickening of Ring Polymers In Weak Extensional Flows
• An O(N^2) Approximation for Hydrodynamic Interactions in Brownian Dynamics Simulations
• Dynamics and Rheology of Ring-Linear Blend Semidilute Solutions in Extensional Flow: Modeling and Molecular Simulations

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• Topological transition in multicyclic chains with structural symmetry inducing stress-overshoot phenomena in multicyclic/linear blends under biaxial elongational flow
• Runaway Transition in Irreversible Polymer Condensation with Cyclisation
• Supercoiled ring polymers under shear flow
• Identifying the Threshold Chain Length for Stress Overshoot in Ring-Linear Polymer Blends under Uniaxial Elongation: The Role of Multiple Threading
• Topological digestion drives time-varying rheology of entangled DNA fluids