Synthesis of narrow-polydispersity degradable dendronized aliphatic polyesters

The divergent dendronization of an ε-caprolactone-based polymer has been performed to provide access to dendronized polymers with sufficient biocompatibility and degradability for use as drug-delivery scaffolds. The synthesis was performed through the tin(II) 2-ethylhexanoate-catalyzed polymerization of a γ-functionalized ε-caprolactone monomer, followed by the divergent growth of pendant polyester dendrons at each repeat unit. The resulting dendronized polymers were obtained up to the fourth generation with molecular weights as high as 80,000 Da and with polydispersities between 1.11 and 1.22. The fourth-generation hydroxyl-terminated dendronized polymer was degradable under a variety of aqueous conditions. A comparison of the dendronization approach with a procedure involving the ring-opening polymerization of a second-generation dendritic macromonomer reveals that the former procedure is best suited for the preparation of this family of dendronized polyesters because it requires shorter reaction times and affords materials with higher degrees of polymerization.