Synthesis And Self-Assembly Of PEG-b-Polyphenylalanine Amphiphilic Diblock Copolymer

Amphiphilic block copolymers are unique building blocks in supramolecular polymer chemistry, both for the generation of highly organized, self-assembled structures and for the energetic and structural control of material interfaces. Poly(amino acid) is a kind of biodegradable materials with low toxicity, excellent biocompatibility, biodegradability and bioabsorbability in vivo. However, their poor hydrophilicity limited their biomedical applications in drug delivery systems and tissue engineering. In this thesis, amphiphilic block copolymers with hydrophilic monomethoxy poly ethylene glycol (MPEG) and polypeptide were synthesized and their self-assembly morphologies in water were observed by TEM.The macromolecule initiator, amine-terminated (MPEG-NH2) was synthesized by Gabriel method, in which the end group of hydroxyl was converted to amino group. The macromolecule initiator was characterized by IR, 1H NMR. The result of these experiments showed that this macromolecule initiator was an effective initiator in ring opening polymerization of N-carboxyanhydrides(NCA).The L-phenylalanine N-carboxyanhydride (b-Phe-NCA) was prepared according to phosgene method (Fuchs-Farthing method), by reacting amino acids with triphosgene. Copolymers with various molecular weights were synthesized by ring opening polymerization of NCA on amino-terminated MPEG. The structure of these copolymers were characterized by means of FTIR,1H NMR and GPC.Self-assembled structures in water of the synthesized diblock copolymers were prepared by the dialysis method. The morphologies of the aggregates were investigated by TEM. The result proved that these amphiphilic diblock copolymers can be self-assembled to micelles, vesicles, rods, fibrilla and nanobelt in water.