Diffusion and Viscosity of Unentangled Polyelectrolytes

Carlos G. Lopez, Jürgen Linders, Christian Mayer, Walter Richtering

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14 Scopus citations

Abstract

We report chain self-diffusion and viscosity data for sodium polystyrene sulfonate (NaPSS) in semidilute salt-free aqueous solutions measured by pulsed-field gradient NMR and rotational rheometry, respectively. The molecular weight of NaPSS is characterized using five techniques. Relationships between Mw and the intrinsic viscosity and diffusion coefficient in excess salt are established. These are helpful for the accurate determination of the molar mass of NaPSS. The observed concentration dependence of ν and D are consistent with the Rouse-Zimm scaling model if the monomeric friction coefficient (ζ) is concentration-dependent. The concentration dependence of ζ exceeds that expected from free-volume models of diffusion, and its origin remains unclear, possibly being related to electrostatic effects. Correlation blobs and dilute chains with equivalent end-to-end distances exhibit nearly equal friction coefficients, in agreement with scaling. Viscosity and diffusion data are combined using the Rouse model to calculate the single-chain dimensions of NaPSS in salt-free solution, and the results overpredict direct SANS measurements of the radii of gyration by a factor of ≃1.4.

Original languageEnglish (US)
Pages (from-to)8088-8103
Number of pages16
JournalMacromolecules
Volume54
Issue number17
DOIs
StatePublished - Sep 14 2021

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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