Paper Number
RS33 

Session
Techniques and Methods: Rheometry & Spectroscopy/Microscopy

Title
Analysis of non-Gaussian deformations from scattering of polymers in extreme shear flows

Presentation Date and Time
October 12, 2022 (Wednesday) 5:05

Track / Room
Track 6 / Mayfair

Authors (Click on name to view author profile)

1. Datta, Anukta (University of California, Santa Barbara, Chemical Engineering)
2. Wang, Xiaoyan (Rensselaer Polytechnic Institute, Dept of Chemical and Biological Engineering)
3. Corona, Patrick T. (University of California, Santa Barbara, Chemical Engineering)
4. van Ravensteijn, Bas G. P. (University of California, Santa Barbara, Department of Chemical Engineering)
5. Weigandt, Katie M. (National Institute of Standards and Technology, Center for Neutron Research)
6. Murphy, Ryan P. (NIST, NCNR)
7. Underhill, Patrick T. (Rensselaer Polytechnic Institute)
8. Helgeson, Matthew E. (University of California, Santa Barbara, Chemical Engineering)

Author and Affiliation Lines (in printed abstract book)
Anukta Datta¹, Xiaoyan Wang², Patrick T. Corona¹, Bas G. P. van Ravensteijn¹, Katie M. Weigandt³, Ryan P. Murphy³, Patrick T. Underhill² and Matthew E. Helgeson^1
1Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106; ²Rensselaer Polytechnic Institute, Troy, NY 12304; ³NCNR, NIST, Gaithersburg, MD 20899

Speaker / Presenter 
Datta, Anukta

Keywords
experimental methods; theoretical methods; polymer solutions; rheometry techniques

Text of Abstract
Applications of high molecular weight long-chain dilute polymer solutions typically involve extreme deformation rates that cause nonlinear deformations and polymer scission. Although various microscopy methods have been successful for resolving single-molecule deformations for specific biopolymer systems (e.g. DNA), these methods are inaccessible to conventional synthetic polymers. Recent developments involving in situ small angle neutron scattering (SANS) measurements in a novel capillary device at extreme shear rates (~10^6 s-1) show promise as an alternative for single-molecule studies. However, previously developed analyses for SANS from deformed polymers has been limited to Gaussian deformations, and thus are inadequate for moderate to high-Weissenberg number flows. Here, we introduce a new modeling framework for comparing the results of scattering experiments to parameter-matched Brownian dynamics simulations that resolve non-Gaussian deformations of polymers at high shear flows. We validate the method using simulated scattering patterns obtained from molecular simulations of polymer configurations in flow. The method is then applied to capillary rheo-SANS measurements on a series of architecturally well-defined polymers at moderate Weissenberg numbers in order to test the influence of chain topology on non-Gaussian polymer deformations. We anticipate that this new analysis method and corresponding experimental observations will inform the rational design and nonlinear rheological modeling for dilute topology-defined polymers to optimize their performance and lifetime in a wide range of applications.