Synthesis and characterization of macroinitiator‐amino terminated PEG and poly( γ ‐benzyl‐ L ‐glutamate)‐PEO‐poly( γ ‐benzyl‐ L ‐glutamate) triblock copolymer

Macroinitiator‐amino terminated poly(ethylene glycol) (PEG) (NH 2 ‐PEO‐NH 2 ) was prepared by converting both terminal hydroxyl groups of PEG to more reactive primary amino groups. The synthetic route involved reactions of chloridize, phthalimide and finally hydrazinolysis. Furthermore, poly( γ ‐benzyl‐ L ‐glutamate)‐poly(ethylene oxide)‐poly( γ ‐benzyl‐ L ‐glutamate) (PBLG‐PEO‐PBLG) triblock copolymer was synthesized by polymerization of γ ‐benzyl‐ L ‐glutamate N ‐carboxyanhydride (Bz‐L‐GluNCA) using NH 2 ‐PEO‐NH 2 as macroinitiator. The resultant NH 2 ‐PEO‐NH 2 and triblock copolymer were characterized by FT‐IR, 1 H‐NMR and gel permeation chromatography (GPC) techniques. The results demonstrated that the degree of amination of the NH 2 ‐PEO‐NH 2 could be up to 1.95. The molecular weight of the PBLG‐PEO‐PBLG triblock copolymer could be adjusted easily by controlling the molar ratio of Bz‐ L ‐Glu NCA to the macroinitiator NH 2 ‐PEO‐NH 2 . Copyright © 2004 John Wiley & Sons, Ltd.