HIGHLY FUNCTIONAL BRANCHED AND DENDRI-GRAFT ALIPHATIC POLYESTERS THROUGH RING-OPENING POLYMERIZATION

Highly branched poly(epsilon-caprolactones) with novel and well-define d molecular architectures have been synthesized by the use of new mult ifunctional initiators. The ring-opening polymerization methods used t o prepare these new structures allowed accurate control of molecular w eight and narrow molecular weight distributions. In addition, the synt hesis of even more complex molecular architectures was possible by the use of 1,4,9-trioxaspiro[4.6]-9-undecanone as a comonomer with epsilo n-caprolactone. After copolymerization, complete deacetalization of th e polyester chains into the corresponding ketone groups followed by qu antitative reduction formed polymers with hydroxyl pendant groups. Wit h this synthetic strategy, significant additional functionality was in troduced. In addition, the pendant hydroxyl groups along the chains ca n serve as macroinitiators for the further initiation of epsilon-capro lactone to prepare dendri-graft molecular architectures. The new polym ers were characterized by H-1 NMR, C-13 NMR, and size exclusion chroma tography (SEC). C-13 NMR spectra clearly showed that the hydroxyl grou ps of the initiators were fully substituted to give polymers with two, four, and six arms.