Structure of Complex Coacervate Core Micelles: AB + C system

Abstract

The effect of charged block length on the complex coacervate core micelles (C3Ms) formed by mixing a diblock polyelectrolyte and an oppositely charged homopolyelectrolyte (i.e., AB+C system) is investigated using dynamic light scattering (DLS), cryogenic transmission electron microscopy (Cryo-TEM), and small-angle X-ray scattering (SAXS). Our findings reveal that increasing the charged length of the diblock polyelectrolyte leads to an augmentation in overall micelle dimensions, core radii, and critical salt concentration (CSC), whereas the charged length of the homopolyelectrolyte has minimal impact on these parameters. This difference is attributed to the relatively unconstrained spatial distribution of the homopolyelectrolyte within the coacervate core. We observed that AB+C C3Ms exhibit a highly swollen core and less crowded corona, consistent with the crew-cut regime of the proposed scaling relationship. Compared to AB+AC C3Ms, AB+C C3Ms show lower coronal chain density, which is potentially attributed to the reduced aggregation number of diblock polyelectrolytes.