Branched Acid-Degradable, Biocompatible Polyether Copolymers via Anionic Ring-Opening Polymerization Using an Epoxide Inimer.

The introduction of acid-degradable acetal moieties into a hyperbranched polyether backbone has been achieved by the design of a novel epoxide-based degradable inimer. This new monomer, namely, 1-(glycidyloxy)ethyl ethylene glycol ether (GEGE), has been copolymerized in the anionic ring-opening polymerization (AROP) with ethylene oxide (EO) or glycidol (G), respectively, yielding branched polyethers, that is, P(EO--GEGE) and P(G--GEGE), that possess an adjustable amount of acid-cleavable acetal units. In addition, a novel class of multiarm star copolymers P(G--GEGE--EO) with acid-labile polyether core and PEG side chains was synthesized by using the P(G--GEGE) copolymers as multifunctional macroinitiators for AROP of EO. The new materials have been characterized in a detailed manner, revealing narrow to moderate molecular weight distributions. The degradation of these polymers under acidic conditions was characterized via SEC and H NMR spectroscopy.