Self assembly of AB block copolymers in a selective solvent of one of the blocks is often used to obtain nanoparticles, that may have interesting properties for electronic or biomedical applications. In dilute solutions, when the insoluble A block forms amorphous aggregates, spherical micelles are usually obtained. We are interested in the case where the insoluble A block self-organizes within the aggregates, because particles with a variety of shapes can be obtained. This has been demonstrated in the case of rod-coil block copolymers where the organization is driven by the packing of the rigid A blocks. Organization within the core can also occur with flexible A blocks, if they crystallize. It was shown that these copolymers form thin platelet structures consisting of chain-folded crystalline domains of the insoluble block, surrounded by a solvated layer of the second block. A particular case of crystalline core is displayed by polylactide which forms a stereocomplex by co-crystallization of the two enantiomers poly(L-lactide) et poly(D-lactide).
Within this context, we are interested in the following points:
synthesis of well controlled block copolymers,
formation on nanoparticles by block copolymers,
stereocomplexation of polylactide.
As an example, the following figure shows an AFM image of a particle obtained by co-crystallization of poly(L-lactide)-block-poly(caprolactone) with poly(D-lactide)-block-poly(caprolactone).