Influence of Multivalent Ion Clusters on Composition and Viscoelasticity of Polyelectrolyte Complexes

Polyelectrolytes (PEs) are water-soluble charged polymers. Complexation between two oppositely charged PEs, driven by electrostatic interactions, leads to phase separation into complex (polymer-dense) and supernatant (polymer-lean) phases. The extent of complexation and phase separation is dictated by solution conditions and the nature of the PEs. PEs are utilized in various applications – water treatment, adhesives, cosmetics – in which they are exposed to monovalent (Na⁺, K⁺, Cl^-) and multivalent ions (Ca²⁺, Al³⁺, SO₄^2-). We have demonstrated that replacing divalent ions reverses the phase composition of PE complexes leading to greater retention of divalent ions in the complex phase. This behavior, in contrast to monovalent ions, led to changes in the viscoelastic properties of these divalent ion-PE complexes. In this poster, these contrasting observations for monovalent and divalent ion-PE complexes will be harnessed to tune the physical (composition, salt resistance) and viscoelastic properties of PE complexes, in the presence of a combination of monovalent and multivalent ion clusters. A combination of thermal degradation and rheology investigations will be adopted to study the evolution of the behavior of PE complexes with increasing ionic strength.