Abstract
Understanding the dynamics of ring polymers is a particularly challenging yet interesting problem in soft materials. Despite recent progress, a complete understanding of the nonequilibrium behavior of ring polymers has not yet been achieved. In this work, we directly observe the flow dynamics of DNA-based rings in semidilute linear polymer solutions using single molecule techniques. Our results reveal strikingly large conformational fluctuations of rings in extensional flow long after the initial transient stretching process has terminated, which is observed even at extremely low concentrations (0.025 c*) of linear polymers in the background solution. The magnitudes and characteristic timescales of ring conformational fluctuations are determined as functions of flow strength and polymer concentration. Our results suggest that ring conformational fluctuations arise due to transient threading of linear polymers through open ring chains stretching in flow.
Highlights
Understanding the dynamics of ring polymers is a challenging yet interesting problem in soft materials
Despite recent progress in understanding the properties of ring-linear blends, a large portion of prior work has focused on the near-equilibrium properties of ring polymers such as equilibrium chain conformation or center-of-mass diffusion coefficient in concentrated solutions or melts
Our results show that the conformational fluctuations of rings exhibit a slower decay and increased correlation time as opposed to a sharp decay occurring over randomly distributed timescales
Summary
Understanding the dynamics of ring polymers is a challenging yet interesting problem in soft materials. We directly observe the flow dynamics of DNA-based rings in semidilute linear polymer solutions using single molecule techniques. Our results reveal strikingly large conformational fluctuations of rings in extensional flow long after the initial transient stretching process has terminated, which is observed even at extremely low concentrations (0.025 c*) of linear polymers in the background solution. The ‘purest as-possible’ ring polymer samples prepared by post-polymerization cyclization of linear chains still contain small fractions of linear chains, even after rigorous purification[12]. From this view, understanding the properties of ring-linear blends is of fundamental interest to elucidate the properties of polymeric samples with mixed chain topology. The slow-down of ring polymer dynamics in entangled solutions of ring-linear blends has been theoretically modeled
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