Molecular dynamics and organization of micellar complexes of poly(acrylic acid) with poly(ethylene glycol)-based surfactants

The structure and molecular dynamics of complexes of poly(acrylic acid) with dodecyl-substituted poly(ethylene glycol)s in aqueous solutions are studied by viscometry and spin probe ESR spectroscopy. It is shown that, at low surfactant concentrations, the complexes have a compact globular conformation. The local mobility of the surfactant molecules in the complexes under consideration is much lower than their mobility in free micelles. As a result of increasing surfactant concentration in solution, the hydrophilic associates of the surfactant micelles with the polyacid having an unfolded coil conformation are formed. In an associate, a significant fraction of poly(ethylene glycol) fragments incorporated into micelles is in the free state, i.e., these fragments are not bound with a polymer chain. The local mobility of the surfactant molecules in the associate is considerably higher than in the complex with a compact conformation, and this mobility grows with the increasing number of micelles involved in the associate.