Self-Salting Coacervates: Interfacial Tension Reveals a Critical-Like Self-Suppression of Complex Coacervation
Year: 2026
Type: preprint
Abstract: Complex coacervation is typically controlled via salt concentration, while the role of polymer concentration itself has received much less attention. Here, we show that increasing polyelectrolyte concentration can progressively suppress complex coacervation in a charge-stoichiometric, salt- free PDADMAC/PANa system. As polymer concentration increases, the coacervate phase swells while the polymer recovery stays nearly constant, and the compositions and densities of the coacervate and supernatant phases progressively converge. At = 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 polymer concentration is not merely a compositional variable, but can itself drive coacervation toward a critical-like, one-phase state by increasing salt-like screening from polymer-derived counterions, analogous to the effect of added salt.
Source: ChemRxiv
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Funder: China Scholarship Council
OpenAlex ID: W7213453078