Characterization of Complex Polymer Self-Assemblies and Large Aggregates by Multidetector Thermal Field-Flow Fractionation.

Micelles prepared from amphiphilic block copolymers (ABCs) have found numerous applications in pharmaceutical, electronics, environmental, cosmetics, and hygiene industries. These micelles, whether in the pure or mixed micelle form, often exist as multiple morphologies (spherical, cylindrical, worm, or vesicular) in equilibrium with each other. However, none of the current column-based fractionation techniques or any microscopic technique are capable of a successful separation, identification, and quantitation of these complex self-assemblies with regards to morphology, size, molar mass, and chemical composition in one experiment. Multidetector thermal field-flow fractionation (ThFFF) is shown to be capable of separating and characterizing not only pure micelles but also mixed micelles prepared from polystyrene-poly(ethylene oxide) ABCs. In addition, multidetector ThFFF is demonstrated to be capable of successfully characterizing multiple micellar morphological evolutions (induced by the addition of an electrolyte) and thus showcasing the potential of this novel approach to monitor the formation of polymer self-assemblies with multiple and complex morphological distributions.