(364h) Understanding Molecular Exchange Kinetics in Polyelectrolyte Complex Micelles

Polyelectrolyte complex (PEC) micelles form when oppositely charged block polyelectrolytes are mixed together in aqueous media. The polyelectrolyte blocks electrostatically associate and phase separate, leading to a dense, polymer-rich PEC core stabilized by a neutral block corona. Considerable theoretical and experimental effort has been focused on the structure of PEC micelles. However, much less is known about the stability and kinetics of the PEC micelles, particularly the mechanism governing the fundamental molecular exchange kinetics between the micelles.

In this work, we developed a PEC micelle platform that is formed by a diblock copolyelectrolyte, poly(ethylene oxide) (PEO) block poly(vinylbenzyl trimethylammonium chloride) (PEO-b-PVBTMA), and a homopolyelectrolyte poly(styrene sulfonate) (PSS), with specifically tailored block lengths and change densities. The structural stability and molecular kinetics in this system were studied using microscopy, dynamic light scattering, small-angle X-ray scattering (SAXS) and time-resolved small-angle neutron scattering (TR-SANS), as a function of various parameters, including core-forming block length, charge density, and salt concentration.

Understanding these processes is pivotal for understanding the long-term stability of the PEC micelles in complex environments, and has important implications for the various intended applications of the PEC micelles, for example the payload release profile of the drugs being carried by the micelles.