Synthesis of end-functionalized AB copolymers. II. Synthesis and characterization of carboxyl-terminated poly(ethylene glycol)-poly(amino acid) block copolymers

AB block copolymers composed of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic poly(amino acid) with a carboxyl group at the end of PEG were synthesized with a-carboxylic sodium-omega-amino-PEG as a macroinitiator for the ring-opening polymerization of N-carboxy anhydride. Characterizations by H-1 NMR, IR, and gel permeation chromatography were carried out to confirm that the diblock copolymers were formed. In aqueous media this copolymer formed self-associated polymer micelles that have a carboxyl group on the surface. The carboxyl groups located at the outer shell of the polymeric micelle were expected to combine with ligands to target specific cell populations. The diameter of the polymer micelles was in the range of 30 - 80 nm. (C) 2004 Wiley Periodicals, Inc.