Clusters of Optimum Size Formed by Hydrophobically Associating Polyelectrolyte in Homogeneous Solutions and in Supernatant Phase in Equilibrium with Macroscopic Physical Gel

• Published in: Macromolecular chemistry and physics 2005-01, Vol.206 (1), p.173-179
• Main Authors: Zaroslov, Yuri D., Fytas, Georgios, Pitsikalis, Marinos, Hadjichristidis, Nikos, Philippova, Olga E., Khokhlov, Alexei R.
• Format: Article
• Language: English
• Subjects: dynamic light scattering; microgels; phase separation; polyelectrolyte telechelics
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.200400164

The formation of finite‐sized microgel particles was revealed by photon correlation spectroscopy in aqueous solutions of hydrophobically associative polyelectrolyte polystyrene‐block‐poly(sodium methacrylate)‐block‐polystyrene. Starting from the lowest polymer concentration (1 × 10−6 g · L−1) up to 1 g · L−1 a single relaxation process dominates the spectrum of relaxation times of the polymer solutions. This dominant mode was attributed to the diffusive motion of supramolecular microgel particles with a size of about 100 nm. Above a polyelectrolyte concentration of 1.0 g · L−1, the size of the microgel grows up to ca. 300 nm. At a polymer concentration 20 g · L−1, macroscopic phase separation occurs: the liquid phase of the microgel‐cluster solution coexists with the phase of the macroscopic gel. Schematic representation of the formation of supramolecular structures in aqueous solutions of hydrophobically associative polyelectrolyte.