Paper of the week: Internally structured nanoparticles and micelles

Block copolymers (BCPs) have the unique ability to form a rich array of self-assembled nanostructures in the bulk and in solution. In the bulk, complex phase diagrams have been mapped and morphologies including lamellar, cylindrical, and bicontinuous (gyroid) self-assembled structures have been identified. Similarly, a variety of structures can be accessed in solution from vesicles to spherical and cylindrical micelles. Recently it has been reported that bulk-type morphologies can be accessed in solution processing of BCPs. However, despite the potential of supramolecular chemistry to dictate the solution self-assembly of hydrophobic BCPs, systematic design rules to control nanostructures on demand are still limited.

Graphical abstract: Supramolecular guests in solvent driven block copolymer assembly: from internally structured nanoparticles to micelles

In the present study, Connal and co-workers established a versatile strategy to prepare a diverse range of self-assembled colloidal nanostructures from the same hydrophobic BCP.  Polymer nanoparticles with well-ordered phase separated morphology were accessed from the solution self-assembly of a hydrophobic polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) BCP. However, the introduction of a hydrophilic guest capable of hydrogen bonding with the pyridine block resulted in an amphiphilic BCP, thus drastically altering the self-assembly behavior and leading to traditional spherical micelles in water. Furthermore, a hydrophobic guest was incorporated into the BCP which formed internally nanostructured assemblies in water with the hydrophobic guest entrapped within the nanoparticle. Their methodology can be used to engineer new systems that incorporate and release guests upon triggered disruption of the supramolecular bonds. Furthermore, the diversity of nanostructures that can be tuned by the incorporation of different guests enables opportunities for outstanding control of the nanoparticle properties.

Supramolecular guests in solvent driven block copolymer assembly: from internally structured nanoparticles to micelles by Daniel Klinger, Maxwell J. Robb, Jason M. Spruell, Nathaniel A. Lynd, Craig J. Hawker and Luke A. Connal, Polym. Chem. 2013, 4, 5038-5042.

Julien Nicolas is a guest web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

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