Synthesis of amphiphilic diblock copolymers MPEG-b-Phe and their self-assembly in water

Poly(ethyl glycol)-b-poly( L-phenylalanine) AB diblock copolypeptides (MPEG(44)-b-Phe(50) and MPEG(44)-b-Phe(7)) were synthesized from Phe-NCA monomer by using alpha-methoxy-omega-2-aminoethyl-poly( ethylene glycol) (MPEG-NH2) as the initiator. L-phenylalanine N-carboxyanhydride( b-Phe-NCA) was prepared with the phosgene method ( Fuchs-Farthing method), through the reaction of amino acids and triphosgene. The macromoleculeas initiator, amino-terminated (MPEG-NH2) was prepared by converting the end group of hydroxyl to amino group. The structure of these copolymers were characterized by means of FTIR,H-1-NMR and GPC. The results of these experiments provided 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.