Synthesis and pH-dependent micellization of diblock copolymer mixtures

Abstract

This work focused on the preparation and the aqueous solution properties of hybrid polymeric micelles consisting of a hydrophobic poly( ε-caprolactone) (PCL) core and a mixed shell of hydrophilic poly(ethylene oxide) (PEO) and pH-sensitive poly(2-vinylpyridine) (P2VP). The hybrid micelles were successfully prepared by the rapid addition of acidic water to a binary solution of PCL 34- b-PEO 114 and PCL 32- b-P2VP 52 diblock copolymers in N , N -dimethylformamide. These micelles were pH-responsive as result of the pH-dependent ionization of the P2VP block. The impact of pH on the self-assembly of the binary mixture of diblocks—thus on the composition, shape, size and surface properties of the micelles—was studied by a variety of experimental techniques, i.e., dynamic and static light scattering, transmission electron microscopy, Zeta potential, fluorescence spectroscopy and complement hemolytic 50 test.