Crosslinkable/functionalizable poly(2-oxazoline)­based micelles

Considering the pseudo-livingness of the cationic ring-opening polymerization of various 2-oxazoline monomers, micelles formed by amphiphilic diblock copoly(2-oxazoline)s are potential candidates for drug delivery. Copoly(2-oxazoline)s of the composition poly(2-ethyl-2-oxazoline)_100-n-block-poly(2-dec-9′-enyl-2-oxazoline)_n (n = 5, 10, 15) were found to form micelles in aqueous solution. The hydrophobic cores of these non-spherical micelles could be crosslinked by the thiol-ene reaction with glycol dimercapto acetate, the ester bonds of which can be cleaved by esterases. While the hydrodynamic radii of the non-crosslinked micelles increased if the hydrophobic block of poly(2-dec-9′-enyl-2-oxazoline) grew larger, the opposite trend could be observed for the crosslinked micelles. In the course of an oil uptake study, the hydrodynamic radii of the crosslinked as well as non-crosslinked micelles increased. In oil-filled micelles of poly(2-ethyl-2-oxazoline)_100-n-block-poly(2-dec-9′-enyl-2-oxazoline)_n (n = 5, 10, 15), the hydrodynamic radii of the non-crosslinked micelles were significantly larger in comparison with the crosslinked ones in case of n = 5 and 10, while the hydrodynamic radii of non-crosslinked and crosslinked micelles were of the same range in case of n = 15. The changes of diameter in micelles with polar molecules such as Zidovudine covalently attached to the hydrophobic core support the proposed antagonism of the inclusion of non-polar/polar molecules into the micelles’ cores and the degree of crosslinking.