Morphology of poly(ethylene oxide)-block-polycaprolatone block copolymer micelles controlled via the preparation method
Résumé
Biocompatible poly(ethylene oxide)-b-polycaprolatone (PEO-b-PCL) micelles have been successfully tested in many fields as nano-carries, especially in drug delivery. We demonstrate herein that using indirect dissolution methods to prepare PEO-b-PCL nano-objects in water, copolymers with volume fractions of PCL (phi(PCL)) ranging from 0.35 to 0.58 self-assemble into spherical micelles when either DMF or THF is used as organic solvent to dissolve the diblocks before the micellization. Striking different, regular wormlike morphologies are however obtained using acetone as solvent for copolymers with phi(PCL) = 0.50-0.58. These results emphasize, therefore, that control over the shape of PEO-b-PCL micelles can be achieved not only by precise macromolecular engineering but also through clever processing strategies.