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Ring polymer dynamics and tumbling-stretch transitions in planar mixed flows.
Charles D Young1, June R Qian1, Michael Marvin2
1Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Physical Review. E
|July 24, 2019
Summary
This study explores how mixed flows affect ring polymers, revealing unique dynamics and transitions between coiled, tumbling, and stretched states. Ring polymers show molecular expansion not seen in linear chains.
Area of Science:
- Polymer physics
- Fluid dynamics
Background:
- Dilute polymer solutions' properties depend on polymer chain dynamics under flow.
- Research has focused on linear polymer chains, but nonlinear architectures like ring polymers show unique behaviors.
Purpose of the Study:
- To investigate the dynamics of dilute ring polymers in mixed flows.
- To compare ring polymer behavior to linear polymers under similar flow conditions.
Main Methods:
- Simulating polymer chain conformations in various mixed flow geometries and strengths.
- Analyzing transitions between coiled, tumbling, and stretched polymer regimes.
Main Results:
- Ring polymers exhibit distinct conformational dynamics in mixed flows, including molecular expansion in the vorticity direction.
- Both ring and linear polymers show a first-order-like transition from tumbling to stretched states, attributed to a dynamic energy barrier.
- Bimodal extension distributions indicate this transition in a specific range of flow conditions.
Conclusions:
- Mixed flows induce complex conformational changes in ring polymers, influenced by topology and hydrodynamics.
- The study highlights similarities and differences in the response of ring and linear polymers to mixed flows.
- A dynamic energy barrier plays a crucial role in the observed tumbling-to-stretched transitions.
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