Conventional micelles receive attention because of their ability to encapsulate guest molecules. While small molecule amphiphiles are known to yield micelles with limited stability, amphiphilic linear block copolymers can be used to improve and tune the size and stability of the resultant aggregates. However, even linear polymers are susceptible to disaggregation at low concentrations.Thus, branched, covalently-bound amphiphilic units are attractive. These resulting �unimolecular micelles� are robust when conventional micelles would disaggregate and exhibit no critical micelle concentration.Dendrimers are highly branched macromolecules, ideal for preparing unimolecular micelles because their end-groups increase exponentially with each generation and are easily functionalized with groups of contrasting polarity. However, potential problems arise if guest molecules are particularly large or require substantial loading efficiencies. One way to construct modular unimolecular micelles with larger void spaces is to incorporate linear polymers between dendritic branching units. For example, unimolecular micelles can be prepared from a star core, such as linear polycaprolactone (PCL) grown from a poly-ol initiator, with dendrons, and an exterior linear chain such as polyethylene glycol (PEG). This design allows for larger void space while still exhibiting unimolecular micelle behavior.These molecules are attractive both fundamentally and practically, however the structural parameters which define aggregation behavior and encapsulation are not well-understood. This study is designed to probe these parameters in order to synthesize molecules for use as drug delivery vehicles, sequestering agents, and surfactants.

Star-dendritic-linear polymers as a modular platform to probe unimolecular micelles

245th National Meeting (2013)

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