Core extractable nano-objects: Manipulating triblock copolymer micelles

We report manipulation of polymer nano-objects by changing solvents through chemically crosslinking the spherical micelles of poly(3-(triethoxysilyl)propyl methacrylate)-block-polystyrene-block-poly(2-vinylpyridine) (PTEPM-b-PS-b-P2VP). In methanol, which is a common solvent of PTEPM and P2VP but poor of PS, PTEPM-b-PS-b-P2VP forms micelles with a PS core. When changing the medium into acidic water, the PTEPM segments further collapse and gelate to form a crosslinked shell outside of the PS core. When the particles are re-dispersed into tetrahydrofuran (THF), the PS segments are extracted out, producing uniform small cavity of few nanometers in each particle. Thus one sample can be used to generate well-defined nano-objects with different appearance by solvent manipulation. The particle structure development has been characterized by transmission electron microscope (TEM), DLS, and 1H NMR. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012