Poly(ethyl glycol)-b-poly(L-phenylalanine)AB dibloek copolypeptides(MPEG44一b—Phe50 and MPEG44-b-Phe7)were synthesized from Phe-NCA monomer by using α-methoxy-ω-2-aminoethyl-poly(ethylene glycol)(MPEG-NH2)as the initiator．L-phenylalanine N—carboxyanhydride(b-Phe—NCA)was prepared with the phosgene method(Fuehs-Farthing method)

through the reaction of amino acids and triphosgene．The macromoleculeas initiator

amino-terminated(MPEG-NH2)was prepared by convening the end group of hydroxyl to amino group．The structure of these copolymers were characterized by means of FTIR、1H-NMR and GPC．The results of these experiments pmvided direct evidence of the formation of the block copolymers．Self-assembled structures of the synthesized diblock copolymers in water were prepared by the dialysis method and the morphologies of the aggregates were investigated by TEM．The results proved that these amphiphilic diblock copolymers Can self-assemble into micelles in water．