Amphiphilic block-co-polymers have garnered a lot attention over the years due to their ability to self-assemble to form micelles and encapsulate guest molecules. The resulting micelles, though, are susceptible to disaggregation under extreme dilution. For this reason, highly-branched, covalently bound-amphiphilic units are attractive because the resulting �unimolecular micelles� are robust when conventional micelles would disaggregate. However, it remains poorly understood how much branching is required for effective unimolecular micelles.  To explore this question within a reverse micelle model, amphiphiles are prepared from a star core, such as polyethylene glycol (PEG) with bis-MPA dendrons, and a hydrophobic exterior such as lauric acid.  A systematic study of structural parameters such as the extent of branching and its location within macromolecular amphiphiles has been designed using a synthesis that is modular at both the core and hydrophilic/hydrophobic interface of the target molecules. For example, core branching can be varied by using a range of the polyol stars while branching at the periphery can be controlled by varying the generation of the dendrons to which the nonpolar end groups are attached. Using this synthesis a modular library of molecules can be rapidly created and analyzed. MALDI-TOF MS then can be used to confirm the exceptional structural purity of these molecules throughout the synthetic process, including dendronization and end group-coupling step.    In addition to establishing a fundamental understanding of branching within self-assembling structures, the specific compounds prepared are expected to have utility for drug delivery and surfactant applications.

Exploring the role of branching within polymeric amphiphiles

248th National Meeting (2014)

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