New amphiphilic triblock copolymer poly(-butyrolactone)-poly(ethylene glycol)-poly(-butyrolactone) (PHB-PEG-PHB) based on poly(-butyrolactone) (PHB) and poly(ethylene glycol) (PEG) was synthesized by anionic ring-opening polymerization of BL initiated with PEG-potassium macroinitiators using tetrahydrofuran as solvent.Many Copolymers with different molecular weight were prepared by adjusting the ratio of monomer (BL) and macroinitiators.Copolymers were characterized by 1H-NMR

13C-NMR

FTIR

DSC

GPC.The DSC curves showed that amorphous PHB hindered the crystallization of the PEG block.The longer the PHB block length

the more obvious the hindering effect.These PHB-PEG-PHB copolymers were self-assembled into nanoparticles with core-shell structure by a precipitation/solvent evaporation technique in aqueous solutions.These nanoparticles were characterized by SEM and DLS.The nanoparticles size was nanoscale.Their shapes were spherical or square.The size and morphology of nanoparticles were related to the initial concentrations of copolymers.The results showed that the size of nanoparticles reduced with reducing the initial concentrations of copolymers.