Paper Number
PO66 

Session
Poster Session

Title
Relaxation dynamics of polyelectrolyte solutions

Presentation Date and Time
October 13, 2021 (Wednesday) 6:30

Track / Room
Poster Session / Ballroom 1-2-3-4

Authors (Click on name to view author profile)

  1. Han, Aijie (Pennsylvania State University, Materials Science and Engineering)
  2. Colby, Ralph H. (The Pennsylvania State University, Material Science and Engineering)

Author and Affiliation Lines (in printed abstract book)
Aijie Han and Ralph H. Colby
Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802

Speaker / Presenter 
Han, Aijie

Keywords
polymer solutions

Text of Abstract
The relaxation times (τ) of polyelectrolyte solutions are unique in the semidilute unentangled concentration regime as τ ~ N2c-1/2 is expected by the Rouse model. The concentration dependence of t has been extensively tested using various polyelectrolyte aqueous solutions, mainly for high molecular weights since they exhibit shear-thinning for at least a decade of shear rates; shorter chain do not exhibit enough shear thinning to evaluate t reliably in commercial rheometers. In this study, we used ethylene glycol (EG) and glycerol as solvents instead of the lower viscosity water. EG and glycerol both effectively slow down the relaxation dynamics and allow the relaxation time measurement for lower molecular weights. Five number-average degrees of polymerization (Nn = 140 ~ 9150) of narrow distribution cesium polystyrene sulfonate (CsPSS) solutions are studied in water, anhydrous EG and anhydrous glycerol using X-ray scattering to determine the correlation length and the rotational rheometers to determine the specific viscosity, relaxation time and terminal modulus. A plot of ξ3τ/N2 vs. c shows that the relaxation time data can be reasonably reduced to a common curve. The terminal modulus G can be perfectly reduced by plotting G/kT vs. c/Nn. Additionally, time-temperature superposition was applied for CsPSS/glycerol solutions from 25 to -5 oC to study the entanglement behavior. Using the overlap parameter Pe, we also estimated the entanglement concentrations of CsPSS in glycerol.