Block copolymer self-assembly in solution

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Block copolymer vesicles (BCVs) are hollow spheres which can be prepared in solution from amphiphilic diblock copolymers. They range in size from ca. 100 to ca. 1000 nm, with a wall thickness of ca. 20 nm. In early work, we have shown that block copolymer vesicles can be prepared very easily by controlling the preparation conditions. They are part of a morphological continuum which includes spherical micelles and rods. Like liposomes, BCVs are promissing in many potential applications in fields such as pharmacology (in drug delivery), cosmetics and catalysis, but are much more stable than liposomes. We have shown recently that many vesicle parameters, such as size and wall thickness, can be controlled by external preparative conditions and polymer composition. We have also shown that it is possible to prepare, in one step, vesicles with different interior and exterior interfaces. Furthermore, we have shown that it is possible to soften the wall on demand to permit active filling with ingredients such is doxorubicin (a cancer killer), to lock in the ingredients by hardening the wall, and than to "re-open it" on demand to release the contents. We have also shown that it is possible to invert the vesicles by exchanging the interior and exterior interfaces. We now propose to explore a "breathing" mechanism in vesicles which allows them to increase or decrease their volume repeatedly by a factor of ca. 10x within ca. 1 minute. This would allow the uptake and release of ingredients very rapidly. We have also learned how to incorporate nanoparticles such as dendrimers within vesicles walls, and now propose to study systematically the inclusion of a number of different species, including catalysts into vesicle walls. In addition, we propose to examine the incorporation of species of specific geometry (e.g. spheres) into block copolymer aggregates and to study the effect of strong interactions on morphogenesis of the resulting aggregates. Several other minor studies are contemplated including the exploration of diffusion through vesicle walls and the entrapment of large molecules inside the cavities of vesicles.