Paper Number
PO9 

Session
Poster Session

Title
Rheology and linear dichroism of dilute solutions of flexible and semiflexible polymers in shear flow

Presentation Date and Time
October 12, 2022 (Wednesday) 6:30

Track / Room
Poster Session / Riverwalk A

Authors (Click on name to view author profile)

  1. Pincus, Isaac (Monash University, Chemical and Biological Engineering)
  2. Rodger, Alison (Macquarie University, School of Natural Sciences)
  3. Prakash, J. Ravi (Monash University, Chemical and Biological Engineering)

Author and Affiliation Lines (in printed abstract book)
Isaac Pincus1, Alison Rodger2 and J. Ravi Prakash1
1Chemical and Biological Engineering, Monash University, Melbourne, Victoria 3800, Australia; 2School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia

Speaker / Presenter 
Pincus, Isaac

Keywords
computational methods; polymer solutions

Text of Abstract
Although the non-equilibrium behaviour of polymer solutions is generally well understood, there remain several unanswered questions for dilute solutions in simple shear flow. Experimental viscosity data exhibit qualitative differences in shear-thinning exponents, shear rate for onset of shear-thinning and high-shear Newtonian plateaus depending on polymer semiflexibility, contour length and solvent quality. While polymer models are able to incorporate all of these effects through various spring force laws, bending potentials, excluded volume (EV) potentials, and hydrodynamic interaction (HI), the inclusion of each piece of physics has not been systematically matched to experimentally observed behaviour. Furthermore, attempts to develop multiscale models which can make quantitative predictions are hindered by the lack of ability to fully match the results of bead-rod models, which represent a polymer at the Kuhn step level, with bead-spring models, which take into account the entropic elasticity. In light of these difficulties, this work aims to develop a general model based on the so-called FENE-Fraenkel spring, originally formulated by Larson and coworkers (Hsieh et al., 2006, J. Chem. Phys., 124(4)), which can span the range from rigid rod to traditional entropic spring, as well as include a bending potential, EV and HI. This model can reproduce, and smoothly move between, a wide range of previously observed polymer solution rheology in shear flow. By showing that one can correctly capture the solvent quality for semiflexible polymer models using Yamakawa’s Quasi-Two-Parameter (QTP) theory, we develop a successive-fine-graining scheme for predicting polymer rheology and conformation, particularly focusing on capturing the Linear Dichroism (LD) of semiflexible polymers. Following the approach of earlier authors, our multiscale model can be used to relate the LD of each segment in our bead-spring chain to the extension of the spring, giving quantitative agreement with experimental data.