Self-Salting Coacervates: Interfacial Tension Reveals a Critical-Like Self-Suppression of Complex Coacervation
Abstract
Complex coacervation, the associative liquid\liquid phase separation of oppositely charged polyelectrolytes, is a widely used physicochemical model for the principles underlying biomolecular condensates and for applications in encapsulation and underwater adhesion. Coacervation is typically controlled through the ionic strength of an added salt, while the role of polyelectrolyte concentration itself has received much less attention. Here we show that increasing polymer concentration can itself progressively suppress complex coacervation in a charge-stoichiometric, salt-free poly(diallyldimethylammonium chloride)/sodium polyacrylate system. As the polymer concentration increases, the coacervate phase swells while the fraction of polymer recovered in it stays nearly constant, and the compositions and densities of the coacervate and supernatant phases progressively converge. At a polymer concentration of 400 mM, the macroscopic phase boundary vanishes and the system reaches a homogeneous, self-suppressed coacervation state. Over this range, the liquid\liquid interfacial tension decreases continuously toward zero, following a critical-like power law with an exponent of 1.43±0.03, close to the classical mean-field value of 3/2. These results show that polyelectrolyte concentration is not merely a compositional variable but can itself drive coacervation toward a critical-like, homogeneous state by increasing salt-like screening from polymer-derived counterions, analogous to the effect of added salt.
Related
- Molecular Insights into Oil–Water Interfacial Behavior of Gemini Sulfonate Surfactants: The Critical Role of Spacer Group
- Effects of Molecular Weight, Charge Density, and Concentration of Cationic Cellulose on Coacervation Behavior in Model Shampoo Systems
- A Molecular View of the Osmotic Response of Polyelectrolyte Complex Coacervates
- Physicochemical Analysis of Coacervates and Premicellar Aggregates in Amino Acid-Based Surfactant Systems
- A Simple Model to Predict Complex Coacervation: Forces as Drivers of Phase Change and Structuration
BibTeX
@misc{li2026selfsalting,
title = {{Self-Salting Coacervates: Interfacial Tension Reveals a Critical-Like Self-Suppression of Complex Coacervation}},
author = {Hongwei Li and Yue Yu and Christophe Schatz and Jean-Paul Chapel},
howpublished = {HAL},
year = {2026},
month = sep,
url = {https://hal.science/hal-05788328v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Self-Salting Coacervates: Interfacial Tension Reveals a Critical-Like Self-Suppression of Complex Coacervation
AU - Hongwei Li
AU - Yue Yu
AU - Christophe Schatz
AU - Jean-Paul Chapel
PY - 2026
DA - 2026/09/20
PB - HAL
UR - https://hal.science/hal-05788328v1
AB - Complex coacervation, the associative liquid\liquid phase separation of oppositely charged polyelectrolytes, is a widely used physicochemical model for the principles underlying biomolecular condensates and for applications in encapsulation and underwater adhesion. Coacervation is typically controlled through the ionic strength of an added salt, while the role of polyelectrolyte concentration itself has received much less attention. Here we show that increasing polymer concentration can itself progressively suppress complex coacervation in a charge-stoichiometric, salt-free poly(diallyldimethylammonium chloride)/sodium polyacrylate system. As the polymer concentration increases, the coacervate phase swells while the fraction of polymer recovered in it stays nearly constant, and the compositions and densities of the coacervate and supernatant phases progressively converge. At a polymer concentration of 400 mM, the macroscopic phase boundary vanishes and the system reaches a homogeneous, self-suppressed coacervation state. Over this range, the liquid\liquid interfacial tension decreases continuously toward zero, following a critical-like power law with an exponent of 1.43±0.03, close to the classical mean-field value of 3/2. These results show that polyelectrolyte concentration is not merely a compositional variable but can itself drive coacervation toward a critical-like, homogeneous state by increasing salt-like screening from polymer-derived counterions, analogous to the effect of added salt.
ER -