Composite Entanglement Topology and Extensional Rheology of Symmetric Ring-Linear Polymer Blends

Abstract

Extensive molecular simulations are applied to characterize the equilibrium dynamics, entanglement topology, and nonlinear extensional rheology of symmetric ring-linear polymer blends with systematically varied ring fraction ${\varphi }_R$. Chains with degree of entanglement $Z\approx 14$ mixed to produce 10 well-entangled systems with ${\varphi }_R$ varying from neat linear to neat ring melts. Primitive path analysis are used to visualize and quantify the structure of the composite ring-linear entanglement network. We directly measure the quantity of ring-linear threading and linear-linear entanglement as a function of ${\varphi }_R$, and identify with simple arguments a ring fraction ${\varphi }_R\approx 0.4$ where the topological constraints of the entanglement network are maximized. These topological analyses are used to rationalize the ${\varphi }_R$-dependence of ring and linear chain dynamics, conformations, and blend viscosity. Complimentary simulations of startup uniaxial elongation flows demonstrate the extensional stress overshoot observed in recent filament stretching experiments, and characterize how it depends on the blend composition and entanglement topology. The overshoot is driven by an overstretching and recoil of ring polymer conformations that is caused by the convective unthreading of rings from linear chains. This produces significant changes in the entanglement structure of blends that we directly visualize and quantify with primitive path analyses during flow.

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• Viscoelastic properties of ring-linear DNA blends exhibit non-monotonic dependence on blend composition
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Cited by in corpus (6)

• Polymer threadings and rigidity dictate the viscoelasticity and nonlinear relaxation dynamics of entangled ring-linear blends and their composites with rigid rod microtubules
• Topological transition in multicyclic chains with structural symmetry inducing stress-overshoot phenomena in multicyclic/linear blends under biaxial elongational flow
• Unraveling the glass-like dynamic heterogeneity in ring polymer melts: From semi-flexible to stiff chain
• 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