Diblock copolymers consisting of methoxy Poly (ethylene glycol) (MPEG) and poly (

prolactone) (PCL), poly(

) (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

-caprolactone or

-valerolactone in the presence of

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

, respectively. The synthesized diblock copolymers were characterized with

, 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, ore 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.