Dynamic Coupling in Unentangled Liquid Coacervates Formed by Oppositely Charged Polyelectrolytes

Area of Science:

• Polymer Physics
• Soft Matter Science
• Solution Chemistry

Background:

• Liquid coacervates are formed by oppositely charged polyelectrolytes.
• Symmetric coacervates have equal charge densities, leading to a single correlation length.
• Asymmetric coacervates possess unequal charge densities, creating complex structures.

Purpose of the Study:

• To develop a scaling theory predicting the dynamics of symmetric and asymmetric liquid coacervates.
• To elucidate the relationship between charge density, structure, and dynamics in coacervates.
• To understand the influence of polymer properties on coacervate viscosity and diffusion.

Main Methods:

• Development of a scaling theory.
• Analysis of polyelectrolyte solutions with varying charge densities.
• Theoretical prediction of dynamic properties.

Main Results:

• Symmetric coacervates exhibit dynamics governed by a single correlation length.
• Asymmetric coacervates display a double semidilute structure with two correlation lengths.
• Dynamic coupling in asymmetric coacervates increases friction and viscosity of high-charge-density polyelectrolytes.
• Predicted dependence of diffusion coefficients on coacervate composition.
• Predicted non-monotonic salt concentration dependence of viscosity in asymmetric coacervates.

Conclusions:

• The charge asymmetry in polyelectrolytes significantly alters coacervate structure and dynamics.
• Scaling theory provides a framework for understanding complex coacervate behavior.
• Findings offer insights into controlling coacervate properties for material applications.