Paper Number
SM37 

Session
Polymers Solutions, Melts and Blends

Title
Direct visualization of single ring polymers in the flow-gradient plane of shear flow

Presentation Date and Time
October 23, 2019 (Wednesday) 2:45

Track / Room
Track 3 / Room 201

Authors (Click on name to view author profile)

1. Tu, Michael Q. (University of Illinois at Urbana-Champaign, Department of Chemical and Biomolecular Engineering)
2. Lee, Megan (University of San Diego, Department of Physics)
3. Robertson-Anderson, Rae M. (University of San Diego, Department of Physics)
4. Schroeder, Charles M (University of Illinois at Urbana-Champaign, Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Michael Q. Tu¹, Megan Lee², Rae M. Robertson-Anderson², and Charles M Schroeder^1
1Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL; ²Department of Physics, University of San Diego, San Diego, CA 92110

Speaker / Presenter 
Tu, Michael Q.

Text of Abstract
Ring polymers lack free ends, thereby yielding a unique chain topology that has fascinated polymer physicists and chemists for decades. Despite recent progress, a complete understanding of the dynamics of ring polymer systems remains elusive. Moreover, we generally lack a robust experimental system for interrogating ultrapure ring polymers in shear flow, even in the dilute solution regime. In this work, we experimentally study the dynamics of ring polymers in shear flow using single-molecule imaging. We designed and built a custom shear flow apparatus that is compatible with fluorescence microscopy and allows for imaging of single chain dynamics in the flow-gradient plane of shear flow. In this way, we directly visualize fluorescently labeled ring polymers in shear flow using this custom-built device mounted on an inverted microscope. Using this approach, single chain conformations can be used to understand the contributions of ring polymer molecules to bulk rheological properties such as viscosity and the first normal stress coefficient in shear. We report the steady-state shear fractional extension, orientation angle, and spatial conformation of these ring polymers in dilute solution as a function of dimensionless flow strength (Weissenberg number, Wi) and compare the results to their linear counterparts. We also report observations on tumbling and tank-treading-like behavior of single ring polymers in shear flow. From a broad perspective, these results provide new molecular-level insights into the dynamics of ring polymers in solution.