Paper Number
SM39 

Session
Polymers Solutions, Melts and Blends

Title
Influence of multivalent ions on composition and viscoelasticity of polyelectrolyte complexes

Presentation Date and Time
October 12, 2022 (Wednesday) 11:10

Track / Room
Track 2 / Sheraton 3

Authors (Click on name to view author profile)

  1. Iyer, Divya (University of California Los Angeles, Chemical and Biomolecular Engineering)
  2. Syed, Vaqar (University of California, Los Angeles, Department of Chemical and Biomolecular Engineering)
  3. Senebandith, Holly (University of California, Los Angeles, Department of Chemistry and Biochemistry)
  4. Srivastava, Samanvaya (University of California Los Angeles, Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Divya Iyer1, Vaqar Syed1, Holly Senebandith2 and Samanvaya Srivastava1
1Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, CA; 2Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095

Speaker / Presenter 
Iyer, Divya

Keywords
experimental methods; polymer solutions; rheometry techniques

Text of Abstract
The addition of monovalent salts to polyelectrolyte complexes (PECs) comprising oppositely charged polyelectrolytes is known to result in diminishing propensity for complexation, leading to complexes with higher water contents and lower moduli. However, the influence of multivalent ions on polyelectrolyte complexation beyond enhanced screening effects has not yet been explored. In this presentation, significant impact of salt cation valency on the viscoelasticity, composition, and ion partitioning charge-matched PECs will be discussed. Preferential partitioning of multivalent cations into the complex phase will be shown to stand in stark contrast to depletion of monovalent ions from the complexes. Concomitantly, electrostatic bridging of polyanion chains by multivalent cations will be described to result in hindered chain relaxation, manifesting as a non-monotonic evolution of the shear moduli of the complexes with increasing multivalent salt concentrations. Relatedly, a failure of time-salt and time-ionic strength superposition approaches in presence of multivalent ions will be demonstrated, underscoring the non-trivial influence of these ions on chain relaxation behavior. Finally, the tunability of viscoelastic properties and PEC phase composition by altering ion composition will be discussed.