Synthesis of methoxy poly(ethylene glycol)/polyesters diblock copolymers and evaluation of micellar characterization as drug carrier

Diblock copolymers consisting of methoxy poly (ethylene glycol) (MPEG) and poly (ε-ca-prolactone) (PCD, poly(δ-valerolactone) (PVL). poly(L-lactide) (PLLA), or poly(L-lactide-co-glycolide) (PLGA) were prepared to compare the characterization of diblock copolymers as a drug carrier. MPEG-PCL, MPEG-PVL, MPEG-PLLA, and MPEG-PLGA diblock copolymers were synthesized by the ring-opening polymerization of ε-caprolactone or δ-valerolactone in the presence of HCl · Et₂O as a monomer activator at room temperature and by the ring-opening polymerization of L-lactide or a mixture of L-lactide and glycolide in the presence of stannous octoate at 130°, respectively. The synthesized diblock copolymers were characterized with ¹H-NMR, GPC, DSC. and XRD. The micellar characterization of MPEG-polyester diblock copolymers in an aqueous phase was carried out by using NMR. dynamic light scattering, AFM, and fluorescence techniques. Most micelles exhibited a spherical shape in AFM. Thus, we confirmed that the micelles formed with MPEG-polyester diblock copolymers have possibility as a potential hydrophobic drug delivery vehicle because a hydrophobic drug could be preferentially distributed in the micelle core.